I'm using Clearcase for source control, and when I right-click on my solution file, there's an option for checking in the files.
Trouble is that immediately after checking in the files, it automatically does a check-out.
How do I keep the files checked in for good?
There should be an option in Visual Studio to prevent an "auto-checkout" after checkins.
However, check also the exact version of ClearCase you are using, because other bugs around checkout/chekin files also exist.
Sure enough, the OP Nav reports in the comment:
The checkbox is in:
Tools > Options > Source Control > Environment > Keep items checked out when checking in
You can see the setting in this article (which was for Team Foundation Server, but which is still relevant for this particular question)