I have a Dell Dimension Inspiron 530S, running Windows XP SP3, with McAfee Internet Security (11.0.578)/McAfee Virus Scan (15.0.291). I have the computer scheduled to run a full scan every week and in the past the scan would take ~3 hours. Now I'm lucky if the scan completes in a day. During the last scan, I pulled up Task Manager to check the usage; the scan was not pulling more than 2% of the CPU and a fraction of the memory. Confused, I checked on it's status under the "Applications" tab only to notice that the process stopped responding with every file. More clearly, it would start scanning a file, hang, resume, move to the next file, hang, resume, etc. I would imagine this is why my scans are taking so long now. I have no problems with the updater, firewall, quick scans, or any other McAfee program. Some help/advice would be very helpful.
You could try virtual tech just to make sure everything is running ok.If that turns out good try to run a free scan with malwarebytes just to see how fast or if it completes.Here is the link to Mcafee virtual tech http://service.mcafee.com/TechSupportHome.aspx?lc=1033&sg=TS
Also you can go to www.malwarbytes.org to download free version of this program.Lastly there are other posts similar to this on this page to the right.It is under more like this.