I had a problem like this, and the solution in
this link[
^] was basically what I did to fix it. I found other links that explained why it fixed it better, but I can't find them. It has something to do with how the path that it's looking for is looking for
...dotnet1\crdb_adoplus.dll
when it should be looking for just
...dotnet\crdb_adoplus.dll
....and it had to do with different versions of crystal or .net working differently. I can't quite remember the specifics.
If this doesn't work, you need to post more information about your project. What version of Visual Studio do you use? What version of Crystal? What version of Crystal were the reports created with? Is it a web project or win forms? Are you having issues between 32bit vs 64bit systems?
Hope this helps.