Client is up 100% totally working this problem solved... but what was really going on? I missed the true cause on this one.
Origional complaint: Acronis backup wont image as there is media problems or bad sectors.A short test backup on Acronis had the same bad sector groups reporting on several files. Usb scanner no longer working. Usb items plugged in hit or miss- wont show files often when plugged in.

Raid 5 machine IBM raid (Dell wkstation). Three Hitachi hds721680pla380 (80 gig) drives

1) RUN 'Check array'- "good". Run Chkdsk on array- Minor file issues only. Acronis says defects. Check each drives Smart- NO errors reported, no pending. Run software disks checker- NO bads- THOUSANDS of SLOWS sector reads.
2) Imaged all drives- NO ISSUES - no bad sectors. Success
3) removed drive 3 from array- introduced new blank drive and asked for array rebuild. TOOK ALL NIGHT. Success- machine boots fine.
4) removed drive 2 from array- introduced new blank drive and asked for array rebuild. TOOK ONE HOUR.Success- machine boots fine.
5) removed drive 1 from array- introduced new blank drive and asked for array rebuild. TOOK ONE HOUR.Success- machine boots fine.
6) machine is working well now- remove antivirus program, garbage start up programs-machines flying... add new AV soft and deliver to client. Acronis happy...scanner back, usb drives report with files... PERFECT!!!


back to drives...why is hardware rebuild good but didn't work with old drives.... Run Atola disk scan - ALL THREE DRIVES HAVE NO BAD OR SLOW SECTORS!
I still have no proof of actual cause of problem. Have old drives. I need education! Love to hear your opinions and would be glad to do checking just to learn more.

That's an interesting situation... I am often asked to report on why a customer's RAID array behaved (unexpectedly?) in a certain way. However, something which few customers realise is that the data needed to understand why something happened, is often destroyed by the changes needed to (hopefully) fix the problem itself! Therefore by the time I get involved, vital information that would be needed to find the cause of the original problem, has sometimes been lost. In short: all diagnosis must be done before fixing the problem, because it may be impossible to do further useful diagnosis afterwards. IMHO that probably applies in your situation

There are a few parts of your posting where I think further detail & investigation of the original behaviour would be needed, to better characterise the underlying problem. Unless you still have a full hardware setup (original RAID controller, original disks, original software like Acronis etc.) which still shows the original behaviour (at least regarding the disk/RAID-related problems), then there is no chance of understanding the original cause(s) with (near-) certainty. In your posting, I see two main areas of unusual disk/RAID-related behaviour during your testing, that would need to be investigated further at that time. However without being able to do further investigation and diagnosis on the original "failing testcase" then, looking at your posting and based on my previous experience, any suggestions of possible causes would just be untestable guesses and hence easy for trolls to argue with and not really useful, nor worth the time.

At least you recovered the customer's data

Thank you, Vulcan for your post. You are correct that the original drives were altered by introducing the new drives- so therefore destroyed without restoring original image- but even that is no guarantee I have reproduced original issue. It is frustrating not to know positively what was actually wrong and be left with only theories as to real problem. Case went well and client is pleased with the outcome. Better to wear Superman cape than be the Villain.

Was a ML-350 or similar server (HP ProLiant) / with 250GB disks by a chance ?

No, not a true Server Hardware or software. It is a Dell Workstation class machine running IBM raid 3 controller opperating under Windows Xp.