AutoCad 2000 files locked

I am having trouble with files created by AutoCad 2000
The program runs fine but when I exit the program and try to open the drawing file it will not open.
I cannot do anythng with the file, i cannot view the properties I cannot copy and paste or anything. If I try to open the file in Autocad it just sits ther and churns (the samething with copy and paste).
The folder which is Documents/drawing always is set to read only!
I can uncheck it and when I go back and check properties it is back to read only
I used cmd attrib -R * /s /d and that did no good.
Autocad saves a bak file, which I can rename and sometimes it works.
I have tried the file on a scan disk and read and write to it and that seems to be ok so I don't think it is autocad but something with the file locking
I use Wincare and I have tried it with antivirus off and firewall off and that doesn't help
I have tried RegCure, Register Boost and Error smart and sometimes I can open the file the first time but when exited and try to open same problem.

I am sure that it is a problem with Vista but I have no clue how to fix it .