Excel files, periodically, taking a long time to save or open
 

This is a new problem since my IT guy loaded Win 7 on my computer. I have
Office 2007 and I didn't have this problem with Vista. Every now and then an
excel file will take up to several minutes to open or save. Sometimes when
it finally opens there will be a message that the file is corrupt. I hit
cancel and the file appears. The spinning green whell is driving me crazy.

My files are saved to a server running MS Small business software, whatever
the latest version is.

Thanks