Without knowing exactly what the host os and version is, and what the QEMU version is, I'd say to make sure these are at the latest versions available. I saw notes to the effect that a fix was put in to later versions of qemu to help OS/2 Warp and ArcaOS.
With QEMU, we typically get our binaries from a german developer who builds the released code, and makes it available to all (for win versions) ... pointed at from the QEMU site.
On the startup string, I'd start adjusting each (one at a time), and seeing what happens; adjust from your working 5.0.6 set, or from one of the sources I suggested.
For example:
- bump the ram to 4096, and retest ... see if amount of ram is an issue.
- change the vga line, to look more like the other examples, and see if that helps
Always just one change at a time, and revert back to your baseline for the next change.
Did ArcaOS offer any help with QEMU ... as in, a startup string that they like?
Hope this helps ...