Same problem here and ive tried all the above, resetting sense, remove battery etc and nothing worked

However i found something last night and turned it on and today its worked perfectly,from its first update this morning at around 5 with lunar graphics,to early morning sun graphic, also switched location from where i live to where i work, and its now updated back to my home place and seems to be working fine updating every 3 hrs automatically, anyway give this a go.
menu > settings > Accounts & sync (check auto-sunc tab is ticked).
Then below is a list called manage accounts, on mine there was 4,google you tube,google mail,stocks and then weather.
I unchecked all except weather and its worked perfectly ever since,lets hope it stays this way
I also noticed on the power widget i have enabled, the refresh tab is now constantly on so it may be that all you have to do is highlight this tab,but now that i have it woking again im just gonna leave it be
Hope this works for you .