I bought a second hand Asus P535 pda only a few days ago and it started hanging immediately. Damn! Got cheated was my first reaction. After reading extensively in this and other forums and from my own experience, I came to the following conclusions:
1. Hanging complaints occurred about a year after the P535 introduction,
2. Hanging occurs most frequently when the unit is moved about,
3. Hanging does not much occur when the battery is fully charged, only when it is partially discharged and in my case when it is a old (1-1/2 years old),
4. Hanging often occurs when the unit is on full power like when the cpu is set to maximum, screen set to full brightness, and when wifi/Bluetooth is on.
Has something to do with the power system, right? The P535 is a speed monster and requires a lot of juice. Old batteries/contact points corrode over time leaving a layer of electrical resistant oxide coating. I also discovered that Asus did a poor job of securing the battery in its place. There is way too much free play in the compartment allowing the battery to move about.
This is what I did to solve the problem:
1. Cleaned out the battery terminals and contact pins on the unit. Ink eraser (does anyone still use this these days?) works best as it acts like sandpaper only a lot less abrasive. Careful with the contact pins – don’t wanna damage these. This is followed up by cleaning with isopropyl alcohol which can be bought in most pharmacies either in bottle or swab form. Don’t use WD40 as it leaves a film of water-repelling substance which may not be so electrical conducive.
2. Secured the battery compartment with strips cut from a thick calling card. These I wedged between the battery and the compartment sides to ensure there is no possibility of movement.
Voila – problem solved for me. Hope it works for you too.
BTW, I’m pretty darn pleased with the unit now. The best part is the price. I only paid a fraction of the price quoted for current models with similar or even lesser specifications.

(For those of you wanting to sync your P535 to Vista/WMDC via bluetooth)


Asus P535 PDA Running Windows Mobile 5 (WM5)
Procedures to Connect via Bluetooth to Windows Mobile Device Centre (WMDC) in Microsoft Vista, SP1

Background: P535 has fixed & immutable COM ports for its ActiveSync aka Serial Port service. PC running Vista/WMDC/BT assigns its own COM ports which is different from that of the P535. So how to sync between P535 and PC?

1. Create a partnership using the USB cable first. Ensure that you are able to do this before attempting to connect via BT.

2. PDA: Start>Settings>BT:

a. General Tab: Current Profile=Default, Turn BT to ON.

b. Accessibility Tab: Check on these items: Allow other devices to connect, Other devices can discover me.

c. Services Tab>Serial Port: Check on the following – Enable Service, Authorization required, Authentication (Passkey) required. Advanced Button: Note that Inbound COM Port=6 and Outbound COM Port=7. These ports are fixed in the P535 and cannot be changed. What you must do is to specify these same ports on your PC.

All other listed services e.g. File Transfer, etc. should be disabled for now so that they do not interfere with the issue at hand. Note that ActiveSync (no longer called this in WMDC) runs through the Serial Port service.

3. PC: Turn your BT on. There is often a dedicated button on the PC for this.

4. PC: Control Panel (CPanel)>Bluetooth Devices

a. Options Tab>Check these items: Allow BT devices to find this computer, Allow BT devices to connect to this computer, Alert me when new BT device wants to connect.

b. Devices Tab>Click on ‘Add’. PC will search and discover P535. Do the necessary to connect to PDA e.g. assign passkey on PC. This will in turn lead your PDA to prompt you for the passkey. Type passkey into PDA and you will have created a bond between the PC and PDA. A window opens stating that these COM ports have been assigned (could well be different on yours): Outgoing=COM5, Incoming=COM6.

Click Properties on the newly discovered P535. Services Tab: These are the services available on BT on P535 and since we have only enabled the Serial Port service (see above) you will see the ‘Serial Port (SPP) Bluetooth Serial Port’ service.

c. COM Ports Tab>The information here confirms the COM port allocations as per above, namely: COM5/Outgoing/[PDA Name] ‘Bluetooth Serial Port’, COM6/Incoming/[PDA Name].

5. PC: The ports assigned by Vista/BT will have to be changed to match the P535 COM port settings as follows (sorry for the crude formatting):

-------------------PDA (Fixed)--------PC: As Assigned-------PC: Change To
Incoming COM---------6-----------------------6-----------------------7
Outgoing COM---------7-----------------------5-----------------------6

Note that after changes, PDA Outgoing (COM7) will match the PC Incoming (COM7) and vice versa.

While the old ActiveSync/WinXP allows you to easily change the COM port, WMDC/Vista does not. However this can still be achieved by some amount of hacking as follows.

Ensure that BT is still turned on. Go to Start>CPanel>System>Device Manager>Ports (COM & LPT). Based on the above assigned ports, there will be two entries (there could be more if other devices are using COM ports):

a. Standard Serial over Bluetooth link (COM6). Right click>Properties>Port Settings>Advanced>COM Port Number.

Change this to COM7. If it happens that COM7 is in use, as was in my case, you will get a warning:

“This COM port is in use by another device … using duplicate names will lead to inaccessible devices and changed settings. Do you wish to continue?”

Go for it! My experience is that the existing device using COM7 (whatever that was) will be allocated another COM port without detriment. But watch out for abnormal PC behavior!

b. Standard Serial over Bluetooth link (COM5). Do the same as above, changing this to COM6. (Update: As the PDA will initiate the connection, this step is unnecessary – COM5 can even be deleted.)

6. PC: Open the Windows Registry: Start>Search for Regedit>Run as administrator

a. Go to HKEY_LOCAL_MACHINE/SOFTWARE/MICROSOFT/Windows CE Services

b. Click on the Windows CE Services icon and look for the string value labeled "SerialPort". It should currently have either "Infrared" or Bluetooth" under the "Data" column. Change this value to “COM7” (without the quotes).

7. PC: After the above changes, reboot (must).

8. PC: Start BT and then WMDC. In WMCE, your PDA will be shown as ‘Not Connected’. Go to Mobile Device Settings>Connection Settings>Check the box: ‘Allow Connections to one of the following’ and select COM7.


9. PDA: Ensure that BT is turned on. Bluetooth Manager>My Shortcuts Tab>New>ActiveSync via Bluetooth>Click Next/Finish to complete connection wizard. Your PDA will discover your PC and prompt you to create a connection shortcut.

10. YOU: Scream for joy. PDA should now be connected to PC via Bluetooth. WMDC shows ‘Connected’ status. You can also confirm connection on your PDA: BT Manager>Active Connections Tab>Outgoing Connections: You will find your PC name as well as the port connected to (COM7).

11. On subsequent connections:

a. PC: Turn on BT & start WMDC.

b. PDA: Turn on BT. BT Manager>My Shortcuts Tab>Tap & Hold the shortcut connection as created above>Click Connect.

12. Note that PDA initiates connection to PC. I was not able to set it such that PC initiates connection to PDA (like when connection is via USB cable) which should result in fewer steps for subsequent connections. I tried setting PC Outgoing=COM6, Incoming=COM7 & Registry>Serial Port=COM6 but had no success. I’d like to hear from anyone who can achieve this.

13. PM me if you want screen-shots to accompany the procedures above.