@Mlehto Unless you use the yet unreleased fixed kernel on a real PegasosII then the kernel up to and including 4.1FEUpdate2 has a known problem with configuring interrupts on PegasosII that BBoot does fix. This was found on QEMU but affects real PegasosII as well so using BBoot on that might help too (and it also boots faster). This can lead to lost interrupts if multiple devices use the same interrupt and that happens more on PegasosII due to how the firmware assigns interrupts. The BBoot README has some info on how to use it on real PegasosII. Removing a card may only help by reducing number of interrupts so the problem happens less frequently but it's not really fixed. Only updated kernel or BBoot fixes that config issue. On QEMU this problem is fixed using BBoot too but interrupts still don't seem to work with passed through graphics cards so that's a different and unrelated issue that is not fixed yet which likely does not affect real machines but specific to vfio-pci.
@Tuxedo I guess you are Windows, right? It is a little bit difficult for me to help you with the information you provide.
I would suggest you get the qemu command with all its arguments (right-click on the vm and select the arguments menu) and paste them in a terminal. Then execute it. This will provide you more information, that will be useful for me to help you.
Also, please download and read the manual, especially the FAQ section, which has a lot of useful information.
If you can't figure out the error, paste here the result, as well as the command that is used.
@Tuxedo The issue you have is with the installed QEmu on your system. Kyvos doesn't download it. This needs to be installed manually. I provide information where to download it in the manual that is available to be downloaded from the same place you got Kyvos. Also, the same information is available at https://github.com/walkero-gr/kyvos