I have been having problem upgrading my Wordpress plugins on a Server 2008 R2 server running PHP in IIS but I finally fixed by updating WinCache.
1) Download the latest WinCache from here
2) Stop IIS
3) Navigate to C:\Program Files (x86)\PHP\ext and copy the updated php_wincache.dll to this folder.
4) Now edit the php.ini located in C:\Program Files (x86)\PHP\ with notepad and add the following line at the end of the file.
extension = php_wincache.dll
5) Save and close the php.ini
6) Start IIS again