Trojan:W32/Crypt.O is a very intrusive adware program, quite similar to another intrusive adware that we detect as 'Trojan.Win32.Agent.cs'.
So far, we found the only reliable way to delete this intrusive adware is to boot from Windows installation CD to Recovery Console and to delete the malicious DLL file from a hard disk. Alternatively you can use ERD commander or a bootable Linux CD to access your NTFS partition and to delete the DLL file. If you have F-Secure Anti-Virus, select 'Rename Automatically' disinfection action for the On-Access Scanner (OAS) and reboot the computer. FSAV should rename the DLL file before it becomes active.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First check if your F-Secure security program is using the latest updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.
The trojan's file is a DLL that is designed to be loaded at Windows startup using the 'Winlogon\Notify' Registry key. As a result the trojan is loaded as the component of one of Windows's system processes. Its removal or modification is impossible when Windows is active. Moreover, the trojan blocks access to its own file, monitors changes to its Registry keys and restores them if they are modified or deleted.