Signal is /constantly/ dropping on iOS 5

[blizeHx]

Hi all,

Since updating to iOS 5 last night (and Jailbroken using redsn0w) my signal has been consistently dropping every minute or so... it just goes through an infinite cycle of saying "Searching", "No Signal", then having 1 bar, then having full bars but no 3G, then back to "Searching" again and repeat.

The only jailbroken apps I have are BiteSMS and SBSettings. Any suggestions on what to try please? For what it's worth I'm on the O2 network (GiffGaff to be precise) which seems to be up for other users.

Thanks

Update: It only happens when 3G is enabled.

I tested this by calling a friend, it was fine for 4/5 minutes with 3G disabled, until I eventually cut it off. I couldn't even call him with 3G enabled.

I'm certain my internet/data settings are correct too, since data does work, just not when I enable 3G. Ah.