I'll leave the detection of possible malware to the Security team. You can try this first though to see if it fixes the problem.....
Open Windows Explorer and right-click the hard drive icon, select Properties and click on the General tab. Disable Allow Indexing Service to index this disk for fast file searching. Wait for the hard drive activity to stop, then repeat for any other drives.
Next go to Start > Control Panel > Admin Tools > Services. Scroll down to Indexing Service and double click it to open its Properties. Click the Stop button and then change the Startup Type to Disabled. Click OK, close down all programs and reboot.