Sometimes, when you try to install a program in Windows, you may receive the following error message and you will be unable to proceed with the installation.
Another installation is already in progress. Complete that installation before proceeding with this install
If you receive this message, the probable cause could be that another installation, repair or uninstallation process would actually be running. If this is the case, wait for it to complete and try again. If no such process is running, here are a few steps you may want to try:
1] Scan your PC with you anti-virus and anti-spyware.
2] Run Disk Cleanup utility or CCleaner to clean up temp files.
3] If you still get the same error message, my MVP colleague 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.
Additional Resource: KB822454.
Related read: There is a problem with this Windows Installer package.