I got the same error on Windows XP (see thread 'LMMS crash on Win XP'. I went so far as to reinstall the OS and still got the same error. No idea why.
Thanks for the reply.
I did install 0.4.9 and got the same result. It did work some months ago, but I removed it. And I believe I did make some changes since then. I'll have to dig deeper. Hopefully, I won't have to do a reinstall.
Thanks.