hello inigo. and welcome to the forums
before we can help you, we will need to know the following things:
Which operating system you are running mame on?
Which version of mame you are running? i know you said that you think it is version .184, but we need to be certain of which version you are running before we can try to troubleshoot the problem.
Are you using any frontend programs? and if so, which frontend are you using and what version is it?
Is Seawolf the only mame rom that you are having this issue with?
answering the above questions will help us get a start on narrowing down the possible issue(s). it may take some time to figure out the cause of your problems, but we will try to get an answer to you as fast as we can.