Excel issue

Just ideas:

Check the Start up directory to see what files are there. Look at Tool>Add-ins as well.
Disable the Office plug for NAV or what ever anti-virus app you're using.

Here is a list of things to try:

www.mvps.org/dmcritchie/excel/slowresp.htm

One suggestion in the forums was to delete:
This stops looking for scheduled tasks on Remote computers. I haven't tried it, so be sure to back up the registry first.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\RemoteComputer\NameSpace\{D6277990-4C6A-11CF-8D87-00AA0060F5BF}

Answer 1 has brought up some excellent points. Additionally, you could change your virtual ram settings so that the range is nil, for example, set both the high and low vram to 4000 and the computer will use 4 gig of your hard drive as virtual ram. The default settings from microsoft stink because creating a range means the comuter actually uses processing time and power to adjust this number between the two parameters.

Are there any extra programs running in the background that are not running on the other machines? This is another thing to check, especially if the users can download other programs and have permission to load them. Of course, many newer programs are run on startup from the registry and not the startup folder. This can be edited, but you ought to take caution in making changes to the registry. Always backup the registry before making changes just in case the changes you make have unwanted side-effects.