I bought the game when it was first released in the UK (Ver 1.0)

I updated to version 1.10 then 1.20.

I then updated to 1.30 and everything was goin cool.

So i recently changed my OS ..

So reinstalled version 1.0 now the fun really begins

When i try to patch it to version 1.20 it says

Verifying Operation Flashpoint, version 1.00...
Error found in file DTA\Voice.pbo (2919681c!=5e01fcab)
One or more files in game instalation are modified or dammaged.
Reinstall game from original CD disc and try again.

Now this was right after i had done a complete new instal from the cd.

Any Ideas..

My System:-

P3@866Mhz
768Mb SDRAM
GeForce2GTS\Pro (with latest driver from Nvidia (DetonatorXp)
Win Xp Pro.
SBLive
3Com 10\100 Combo Networking Card.

The Machine is part of a 3 computer LAN at home and all was workin fine untill this happened, I know it aint a problem with Xp cause it is on one of the other machines and works fine with OFP..