You may wish to scan your PC with a reputable online scanner... the following are thorough, if you are having a lot of problems or if you have no resident antivirus, then it is recommended that you scan with more than one scanner.
Jotti's malware scan 25mb limit per file
VirusTotal 32mb max file upload
VirusTotal -Firefox Add-on
Metascan Online 40mb max upload
VirScan 20mb file size
Virus-
VirusChief
Dr.Web online scanners
Kaspersky This is a very thorough scan but will not clean your computer.. however it does produce a detailed log for posting on forums. -
Free Website Security Tools and Services
Freeware open source virus software ClamAV

Jotti's malware scan 25mb limit per file
Code:
http://virusscan.jotti.org/en
VirusTotal 32mb max file upload
Code:
https://www.virustotal.com/
Code:
https://www.virustotal.com/documentation/browser-extensions/
Metascan Online 40mb max upload
Code:
http://www.metascan-online.com/
VirScan 20mb file size
Code:
http://www.virscan.org/
Virus-
Code:
http://www.virus.org/
VirusChief
Code:
http://www.viruschief.com/
Dr.Web online scanners
Code:
http://vms.drweb.com/online/?lng=en
Kaspersky This is a very thorough scan but will not clean your computer.. however it does produce a detailed log for posting on forums. -
Code:
http://www.kaspersky.com/virusscanner
Free Website Security Tools and Services
Code:
http://www.malwarehelp.org/freeware-open-source-commercial-website-security-tools-services-downloads.html
Freeware open source virus software ClamAV
Code:
http://www.clamav.net/lang/en/