I am going to tell you the exact same thing someone told me when i was getting "refresh error: failed to fetch xxxxxxxx"
I used to only have cydia and use cydia but...
Go get Rock! lol
Make sure you get "RockApp" looks like a pic of finder icon. Or get it from the black rain app.(though with cydia having so many errors/problems install from there might not be reliable lol)
I love Rock. its so much better then cydia. i keep both but im probably going to uninstall cydia because it is such crap software.
Make a rock account from the rock app, and then it will sync everything you have installed/added from cydia to it and create a backup to the account you created(so if you ever restore/update it will be linked to your account for easy reinstalling!) But you must re-add any manual sources!
Rock is much faster,sleeker,more options. If you have tried it in the past, try it now it might work better. Current version is Rock 2.20.9.
I have an ipod touch 3g 3.1.2 jailbroken with blackra1n RC3 and have not had 1 problem with it yet. Results may vary based on device,firmware, and what you used to jb it.