Moved to Malware Discussion > Home User Assistance.
A name for the spyware would be useful and details of your operating system and service pack would also help.
McAfee have a new tool to help fight malware & fake anti-malware pests which usually get past most antivirus applications. It's called GetSusp.
You have to go to the GetSusp Group to get the latest version and apparently they are now having a lot of success especially with all these new and prolific fake anti-malware threats.
Membership is not required. You can also find support for it in that group and provide feedback. The actual download is available
Please read this McAfee article: Required Reading - Home User Assistance, Malware Troubleshooting
If you can isolate the malware that isn't being detected you can try submitting it to McAfee Laboratories.
You could also try scanning using the FREE version of THIS tool. Update it before running and let it remove anything it finds and reboot if it asks you to do so.