Auto restart after few minutes connecting to WI-FI network

I have purchased my Samsung Galaxy S independently without any contract, so recently i tried to browse without using any sim card. When I turn on the phone the start shows little bit sluggish with "System process not responding sign". The worst part is whenever I have successfully connected to wi-fi network few minutes later it always restart to dark lock screen page , and with media scanner  rebooting again like the phone just been turned on. Please help me for technical solution.

Hey... Yes, found someone that shares my problem/bug... I also have that international, unlocked first day bought GT-i9000 (well I don't know for you about that) which, for a moment now, can't use with wi-fi on as it will "reboot" (let's say "soft restart") exactly after X amount of time, about a minute, which is a race against the clock to reach that website of read that e-mail.

I'm about to just factory reset the whole thing and remove that custom firmware stuff, CFLagfix and Samset1.9CFW. I think my bug started occurring approximately at the time when I flashed and rooted the thing.

With or without a SIM card in it, with data mode deactivated, it won't work.