Data1.cab Error

Hello,
At work my boss opened up a email that had his name as the handle it was a zip file and he unzip it.It prompted this file will replace files with a unknown format and then the service pack 4 install prompt came up.It already had sp 4.I tried to load Sp4 again and it would not go.I had to shutdown and restart.SP4 was still loaded so I assumed everything was ok.
Then the next day his autocad went nuts moving all over the place.So he uninstalled it.Today he tried to reinstall(CD) and half way through the installation got a Error 1335 Data1.cab is missing or corrupt.So we had to abort
I suggested he could reinstall windows which I cautioned him.He wanted too. So with the operating system running we loaded the windowsnt pro and did the "upgrade"(why do they call it a upgrade that's what we had running?) not changing the programs or saved files.
The reinstall went ok except for a VPN software prompt looking for a dll. file.I did not have the file so we ignored it.When we restarted we got a blue screen with kernel/phys memory dumping to hard drive which counted down to 100 and windows booted.Everthing looked ok all the programs still there and folders so we tried loading Autocad again and got the same error 1335 data 1.cab missing or corrupt.So I removed the other add on programs from add/remove and tried again and it worked.
Upon reeboot I got a Page fault in non page area blue screen count down to 100 and restart just fine.
I then d/l Microsoft antispyware install sheild came up and half way through install same error 1335 data1.cab misssing or corrupt
Due to a error 1335 Data1.cab is missing or corrupt. I reinstalled windows NT pro(not a clean install)I had tried again to reinstalling autocad and I got the same error.
I heard Firewall/antivirus could cause this or a bad cd rom or a bad cd.I don't think that's a problem.I heard Install sheild can do it which is what Microantispyware uses.
Searching the net I found lot's of people with this issue but a lack of solutions.
Thanks

 

I am getting very frustrated trying to resolve the 'error 1335 Data1.cab is missing or corrupt' issue. I get no help from the Microsoft site. Since you have dealt with it would you tell me what you learned or did to correct this? There isn't much on the web that I've found and so far, no solutions. I'm to the point where I might change out the hard drive. Any help is very much appreciated. I am using XP Home Edition.