Are these Messenger Service pop-ups like click here - if so disable.
If not, download Ewido Anti-Malware trial version click here
When installing, under 'Additional Options' untick 'Install background guard' and 'Install scan via context menu'.
Launch Ewido by double clicking the icon on your desktop. The program will now go to the main screen. You will need to update Ewido to the latest definition files. On the left hand side of the main screen click update then click on Start Update.
Then select 'Settings'. Under the bottom section 'What to Scan?' make sure 'Scan every file' is ticked. Select 'OK' and you will return to scanning options. Click on Complete System Scan and the scan will begin. This scan can take quite a while to run.
While the scan is in progress, you will be prompted to clean the first infected file it finds. Choose 'Clean' (or 'Delete' if 'Clean' is not an option). Then put a tick next to 'Perform action on all infections'. Doing this enables the scan to proceed automatically until its completion. Click OK.