Hi, and welcome to the board.
Do you have a folder called Temp in your C:\Windows directory?
If you don't, create one.
Next, do this:
Go to Start/Run, and type notepad /autoexec.bat (space after 'Notepad'!)
Your autoexec.bat will now open in Notepad.
Look for lines that start with SET TEMP= and SET TMP=.
Change them to read:
SET TEMP=C:\Windows\Temp
SET TMP=C:\Windows\Temp
If the lines aren't there, put them in.
Go to File -> save.
NOTE: If Windows is installed to a different location, change this accordingly, so that both point to the \Temp folder that is located in the folder where you have Windows installed.
Restart your computer.