Was there a time when this system under your ownership of it didnt do this, and any history of it happened after a specific event such as bad storm etc, or is this a computer you acquired that has had this issue since you acquired it?
Looks like a corrupt BIOS flash maybe... What happens if you tap the key to get into BIOS, does it let you in and when you get there if you can get there does everything look ok?
Other possibility is a RAM issue where shared memory has an issue at that allocated space in system RAM. Memtest86 would be able to test for this as a culprit. I have seen systems behave fine most of the time and an issue with a memory address causes strange stuff that doesnt crash the system but makes for weird stuff.
Its assumed that the CMOS battery is healthy and not the cause.... If unsure you can swap the CMOS battery and see. Also can clear the CMOS and see if that corrects it via a jumper setting or push button on motherboard or removal of CMOS battery which might be a 2032 coincell.
I assume you dont have any overclocks in place and this computer is running the correct normal clock speeds to not make anything work outside of normal operating conditions, as for overclocking can cause weird stuff too.
Lastly, If the system has a video card, swap with a different video card and see if you get same results. If integrated video is available vs use of a video card try that and see if it clears it up. If its running off of integrated video and you can add a video card, add a video card and see if it cleans this issue up. *Slim chance it could be video card related.
If this was a system that someone used a BIOS hardware rewire hack with push button and correct timing to crack a locked password protected system, it can cause stuff like this too. But assuming this system was never one of those. And on that subject cant talk any further about it because cant give any other viewers of this hints on how password protected systems at the BIOS level can be cracked = unlocked for use vs paperweight.
