imranzero
the important step is until u can setup Andrioani OR. then try boot into Andrioani OR until u get the MENU.
after get the menu, u can go to nandroid and make backup for current ROM.(in case your new ROM not working, u can revert back to ori ROM by restore nandroid).
after that step, any ROM can be installed.

important tips to know your ROM file type:
1. nandroid backup(need to unzip the file):  need to put the file under nandroid folder in /sdcard/nandroid/openrecovery/xxxx folder/*.img and *.md5
if you unzip this file, you will find alot file with .img and .md5

2. update .zip(dont unzip.let it in .zip):  need to put .zip file under /sdcard/OpenRecovery/updates/xxxx.zip
if you unzip this file, u will find 2 folder (META-INF and system) and 1 image file (boot.img). so confirm this is update.zip file

then in Andrioani OR to update new rom:
a)choose nandroid for nandroid restore.
b)choose update for update .zip

imranzero, that's the way it is. Android automates things, when you have too much of free memory, some app will auto launch.

Task killer is not what you need. You need Autokiller Memory Optimizer. It actually set your core Android settings - I malas nak explain sini, go download install and set it up first. You will get more free RAM afterwards.

So how's CM6?

hm I don't know about that.. Milestone comes with a proximity sensor, so during a call and if you place the phone near to your face, it will auto off the screen.

This didn't happen on your case?

There is a manual workaround -  get "myLock phone tools" which locks the touchscreen once a call is placed after the phone screen goes blank.  You have to push the camera key to activate the touchscreen again.

But I would highly recommend that you ask the dev or the forum which you got the ROM from (XDA I presume?). Maybe they have a fix which you didn't apply after flashing the ROM.