In early NT and XP, if a Setup.exe file existed in the folder as the next installer ran, you could call the wrong file and either crash the install process or uninstall other software.
Workaround / Fix:
As a rule of thumb, check the temp directory before running any installation programs or unzipping installation programs. The directory in question varies in location dependent upon who you are logged on as. To find the directory, open Windows Explorer, Click on Tools/Folder Options, then on the View tab, and then choose Show hidden files and folders. At this point, the Local Settings folder will show up within your current logon username folder. Browse to: C:\Documents and Settings\username\Local Settings\Temp and delete all old items out of the Temp folder