Network Connection Error after 4.1 Pwnage Jailbreak

[pattoniscool]

First time Jilbreak on 3GS, everything went fine, loaded Cydian, installed MyWi, now every so often I get the error message about no network connection even though I show full 3G bars. Have done hard resets, reset network settings to no avail. If I do a hard reset or reset network settings, it will work for a while and then start giving the error again. Any help would be greatly appreciated, thanks.