If whenever you try to install a Microsoft Application or a new program you get the following error messages and you are unable to proceed with the installation:
“Another installation is already in progress. Complete that installation before proceeding with this install.”
Here are a few steps you may want to try:
Scan your PC with you anti-virus and anti-spyware.
Run Disk Cleanup utility or CCleaner to clean up temp files.
If you still get the same error message, my MVP collegue Vijay suggests that you do the following:
Type services.msc in start menu and hit enter to open Services.
Scroll down to the Windows Installer service and double click on it.
Stop the service and then restart it.
Now try to install the program. Should help.
Addl Resource: KB822454.