This is an installer-related error. It may occur if you are attempting to install a version of Microsoft Office, but another program is interfering with the installation process. A common cause of this error is when an antivirus program is running in the background while you are attempting to install the software.
There is a solution when An internal error has occurred.
To remedy this situation, first try backing out of your install process, and then turn off your antivirus software and any other programs that are running in the background. Then attempt your install again.
Alternately, you can make sure that there are no background programs that could interfere at all, by re-starting your computer with a “clean boot”. Doing so will start the computer without any background programs running. The procedure for starting with a clean boot will vary depending on the version of your operating system. In Windows XP for example, click Start, Run, and then type msconfig and click OK. Go to the General tab, click the Selective Startup, clear Load Startup Items, and click OK. Restart the computer and it will launch without any of the background programs running. Having executed a clean boot, then you can attempt your install again.
TipFor more information, please see: How to fix Installation error #2755