The first thing
Backup any important data, docs, email, photos, music, etc.
Then right click command prompt shortcut and choose run as admin
then type sfc /scannow
depending on the results
run chkdsk c: /r from a command prompt
run defrag a couple three times
How does the computer run, other than while you are attempting software installs? Check the event viewer, windows logs, application and system logs see if anything there raises an eyebrow.