I had this issue for about a week.  Tried to ignore it for as long as I could.  But alas, today I had to get to one of the portals.

Basically, whenever I would try to go to one of our corporate portals, my IE would just sit and spin (no pun intended).  I was able to get to content that was directly bookmarked, and I was able to get to some of my personal portals (yes I am that geeky).  I had no idea why.

Some searching yielded next to nothing, but it was a pretty feeble attempt.  Tried some of the basics.  Rebooted, laptop had been on for a couple weeks (I use sleep alot), so I thought maybe some hidden monster was eating sharepoint.  No avail.  Did all my non-critical windows updates that might apply, nothing.  Finally, I tried clearing my temp inet files, and alas, I can get back in.

I know the temp inet files was a fix for view source, but now we can add it to the list for a spinning portal also.  I wish IE would see this error, and give us some kind of warning.  It must know somewhere in the background that it was trying to write to disk, and couldn't.  Oh well.