Are you using any plugins in the songs that play while OpenMPT crashes, and if yes, which ones?

<blockquote>Save as MP3 is always grayed out.</blockquote>
You most likely don't have an MP3 encoder installed. Put LAME's lame_enc.dll in OpenMPT's application directory if you need MP3 export, though I would generally recommend exporting to WAV first (with normalizing) and then using an external program like lamedrop or oggdrop for creating mp3/ogg files.

No, no VST plugins are being used. It's weird i can't export to MP3 because of the lack of the LAME encoder, because it used to be there.

<blockquote>No, no VST plugins are being used.</blockquote>
Please get the latest test version (http://sagagames.de/stuff/mptrack.exe); when it crashes, it should create a memory dump in the temp folder (a message with the exact location should be displayed). Upload this memory dump to the issue tracker.
Also, it would be handy to know which output device type (waveout/directx/asio) you have selected.

<blockquote>It's weird i can't export to MP3 because of the lack of the LAME encoder, because it used to be there.</blockquote> You either need an ACM codec to be installed or lame_enc.dll to be present in OpenMPT's folder, if either of the two is not true anymore, MP3 export might not be available.

I would love to upload the file to the issue tracker, but i can't because the Issue Tracker doesn't allow me to add DMP files. I'll change the extension to TXT, if that helps.

Also, i use Primary Soundcard (DX Logo)

Please compress the file using zip/7zip.

Zip file is up.

Edit: 176400Hz + Quad 32 Bit seems to work in both Player Settings (Export as WAV still fails) but creates undesired lag. Changing to Stereo 32 Bit makes the lag dissapear.

Can you please also provide a copy of your mptrack.ini? This file is located in %APPDATA%\OpenMPT (unless OpenMPT is installed in portable mode).

But ofcourse.

Hmm, nothing too suspicious. Is it correct that you have increased the mixing quality to something higher than 50 KHz when this crash occoured?
And again, it would be good to know what kind of audio hardware you have installed, since the crash doesn't happen here, even when increasing audio quality as you described.

Soundcard: USB Sound Adapter CSOUNDU C08-041 (In Windows it's called 7 - C-Media USB Audio Device (Generic USB-Audio))
Above 176400Hz it crashes.

I think this might be related to issue 0000329, which has been fixed in the meantime. Does this still happen to you in the latest version?

Please check if this still happens in the latest versions.

I'll close this for now as there is a big chance that this has actually been fixed. If the bug reoccours, please let me know!