Your computer is most likely a Windows computer judging from your error message. Windows has several different areas it stores its temporary files (these are like scratch paper for doing computations). Good applications cleanup from themselves and delete their temporary files, when they are done with them. However, not all applications are so nice. You can look for temp folders off your root director (most likely c:/) and also in your own Document and Settings folder. You can select the files in these folders and delete them. Any temp files being used in these folder will not be deleted.