Sorry to overload load.
I trawled the forums and downloaded Malwarebytes Antimalware.
It found a trojan. log below.
If no more is needed I won't be offended if there are no replies

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Malwarebytes' Anti-Malware 1.24
Database version: 1015
Windows 5.1.2600 Service Pack 2
11:12:19 AM 2/08/2008
mbam-log-8-2-2008 (11-12-19).txt
Scan type: Full Scan (C:\|D:\|E:\|F:\|)
Objects scanned: 83828
Time elapsed: 44 minute(s), 48 second(s)
Memory Processes Infected: 0
Memory Modules Infected: 0
Registry Keys Infected: 0
Registry Values Infected: 0
Registry Data Items Infected: 0
Folders Infected: 0
Files Infected: 1
Memory Processes Infected:
(No malicious items detected)
Memory Modules Infected:
(No malicious items detected)
Registry Keys Infected:
(No malicious items detected)
Registry Values Infected:
(No malicious items detected)
Registry Data Items Infected:
(No malicious items detected)
Folders Infected:
(No malicious items detected)
Files Infected:
F:\Program Files\Adobe\Acrobat 6.0\Reader\PDF417Encoder.dll (Trojan.Downloader) -> Quarantined and deleted successfully.