Pidief.A is a Trojan horse that exploits the Adobe Acrobat Mailto Unspecified PDF File Security Vulnerability (BID 25748) in order to lower security settings. It may also download more malware on to the compromised computer.
Spyware Doctor can automatically remove the Trojan. Even if you remove it manually, we recommend you should use Spyware Doctor to make sure it's completely removed from your system and will not be reinstalled by itself.
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Removal Instructions for Emerging Adware & Spyware
