i found this on google android help forum from Rade 113. and it works perfectlly, my phone is now back to normal, hope it works for you guys, good luck.
I've been having the same problem with my Samsung Galaxy S, but doing the below seemed to solve the problem:
SETTINGS > APPLICATIONS > MANAGE APPLICATIONS
Once in manage applications, click the menu button and select filter and filter by all.
Now delete the data AND cache for the following applications (if you only get the option to delete one or the other, then do what is available):
Google Talk Service
Google Talk Storage
I don't know if it was a combination of all of them or just one, but when i had tried doing the above for just download manager and Google apps it didn't work, so i tried anything to do with the internet and anything that might keep info to do with my account.
Hope this helps!