Shoot!!! Second day facing the same issue.

Data connection suddenly lost without warning. Need advice on this as the telco blaming the phone.

Phone is on stock ROM.

Mine is Blue in Cyberjaya and My friend using yellow at Kelana Jaya.

HUrm... I think is got to do with the apps it think but could not pin point which one. haih

I believe it's the same issue I reported in the previous thread. Not sure if davidlow7 is facing the same issue, since he complained about connectivity as well.

For me, the H, H+, 3G, E logo will suddenly disappear and I lose the data connection.

I found that Anand of anandtech also faced the same problems. I doubt it's the network. Someone suggested switching modem/baseband. I'm thinking of doing that but haven't gotten around to doing it yet. Too much to learn and not enough time to learn how to do it yet. lol. Rooting, flashing, cwm, titanium, etc etc etc. 

Edit: I'm using stock + upgrade to KH2 via Kies. This happens before and after I upgraded.

I have no power saving apps, but have the default power saving function ticked. It has no options to kill data connection, though, and my batt was at 80%, way too high above the threshold and I wasn't idle, but busy downloading.

Since me, aiman and Anand are on different carriers, i doubt it's the network.

Yup.. Are you refering to battery bar?

But mine it does not turn off the data connection, it straight away stop having connection even though i off and on again the data packet. need to restart the phone then it get back to action.

I am also facing the same problem, i am using yellow teleco and sometime i just lost the mobile signal completely.
i am on stock 2.3.4 rom with just some normal apps no battery saving apps.

You've been very helpful but as silly as it sounds, may I know where I can get access to the "My Files"? It is under SETTING?

You can laugh at me at least I learnt something here from others. I'm kind of lost here and I don't have much time learn about the phone. Can you help me, please?