Dotmad.net

As it turns out, there is a file called ExpansionsXML.xml in your “local settings” folder, which gets written by VS a lot, thus slowing down the application - marking it as “read only” solves the problem.
(Thanks to Kim’s post)

Taken from Scott Hanselman’s blog.

I tried installing new version of the Visual studio, and everything went fine, up to the point of trying to load the help, which resulted in “Microsoft document explorer” (dexplore.exe) exception.
I tried re-installing the entire studio - didn’t work.
I tried removing the document explorer, deleting all traces of it in the file system and registry, and installing it again - failed again.
After a lot of searching I came up with a post claiming this may be the result of a rootkit (although the error described was not the one I got).
I ran several tools, including ad-aware, spybot, and RootKitRevealer with no results.
Eventually I tried running Avast anti-virus, and it found two suspected files, and deleting them fixed the problem.
In case someone else encounters the problem, here is the log:
Sign of “Win32:Zhelatin-BZ [Wrm]” has been found in “C:\System Volume Information\_restore{FF2C8423-2E23-48A7-93CC-591C2B4A4764}\RP465\A0084610.exe” file.
Sign of “Win32:Rootkit-C [Trj]” has been found in “C:\WINDOWS\system32\tobhunfb.rlo” file.