mhookem has a good point...but I would correct one step, and then, maybe, go a bit further...consider the following...
1. what extension was the problem file saved under? ...did it match the extension of the files that that program was supposed to save it under?
2. is it a "common" extension, or proprietary? ...i.e. can more than one prog open the file, or just one specific program?
3. was there a function of one prog to influence the behaviour of another?
4. was there a function allowing one prog to serve as a pseudo-opener for another?
5. was the second prog dependent upon the first for some part of its functioning...and thus they are co-dependent now?
6. is the uninstalling of one or the other program affecting the working of the remaining program?
7. was the saved file correctly associated with the program it was created under?
8. were different extensions experimented with while trying to open it? Hypothetically
, install both programs, then try to open the bothersome file [I'll call it file-Z] up. If Z opens, then you know that that prog has been set to be the default opener-upper. Then take the *.exe file from the program's install folder and set it aside in a new folder maybe called "X-file" which is in the same folder that the *.exe file was in...for safe keeping. Try to open Z again. If it does not open, move to plan B...because you already know that the *.exe file works ...and "we" are trying to find an alternative Z opener-upper... Note the extension of file Z, and like "mhookem" said, try now to open with
another program...but do not tick off the box, because you will then lock the file extension to only one opener-upper
...leave it unchecked and if it works, make a mental note of it...if it does not, then you are still open to offers on the next go-round. Now, which "other open with" program will "we" use...well, that's the issue, isn't it? To find one...so back to the extension... go to a site that identifies extensions and then tells you which program[s] it will default to it...e.g. ... here are just a few tools that may help...no promises...see if there is more than one prog to open any given file...
-http://mark0.net/soft-trid-e.html & Marco Pontello's Home - Software - TrID - Files Extensions and File Type Definitions list
There are many more out there...
If you are totally conflabulated...contact the vendor and ask for its advice...something you probably should have done in the first place, but then we would not have had this nice chit chat...