Invalid dll version message

I’m getting the invalid dll version message with my burned copy of Half LIfe Opposing forces. The copy was made with the cracked opfor.dll file but even a copy made with all the original data still gives me the same error!
Is this error generated by the safedisc protection or what?

This may be a query that has arisen before,but as a newcomer to this forum I’d appreciate some help…only one coaster so far!

Well, you have to be more specific;

Whats the name of the dll?
And is it when you want to play halflife or when you want to play counter-strike / team fortress?

Thanx for the reply Alchantra…
The error occurs as I try to run the Opp.forces program from the desktop shortcut. I’ve modified the shortcut with the"-dev -console"configuration,and, as the program initiates, it drops out after about 2 paragraphs of setup instructions,with the error message.
I assume its objecting to the modified opfor.dll in the gearbox/dll folder,but it doesn’t tell me !