Today I upgraded an old ASP.NET project to 2011 vol 1 with the latest service release.  It uses the UltraWebGrid control.  This app worked fine before the upgrade but afterwards it would load the grid properly on form load, and would then hang indefinitely on the first postback.  FireFox works fine.

I did not find any good posts on the solution and since the UltraWebGrid DLL seems to be absent from 2011 vol 2 this may be the final supported release for UltraWebGrid.  Hopefully taking the time to post this will help someone else.

The solution was found using a free tool I highly recommend... Fiddler.  Fiddler indicated that the last HTTP GET was to the the AJAX progress indicator GIF (even though I am not using AJAX).  Sure enough it was not in my images directory.  I found that the C:\Users\Public\Documents\Infragistics\NetAdvantage 2011.1\ASP.NET has many more images, scripts, and css than I found in my program files directory and copied all the stylesheet images into my ig_res folder.  Next Fiddler indicated a similar hang on a css.  Rinse, repeat.

IE 9 is working fine now.