Have you got any external Hard drive connected to the system? Or anything USB. If you do disconnect and reboot.
If you don't, check the BOOTING order in BIOS. Might have changed after the BIOS upgrade.
And if all that fails, and you didn't have a RAID configuration, try SET SATA AS IDE in BIOS.
P/S You might loss your data if you play around... Do you have a back up?
Thanks for trying to help!
No, I don't have any external drive connected to the machine. Only two identical hard drives configured for RAID1 (mirroring).
I suspect the BIOS has a minor bug. I presume they've simply forgotton to explicitly disable the cursor before starting to boot from any source. So if any "special" conditions are met (like a particular boot sequence or anything) the cursor keeps being enabled.
Can someone reproduce the problem at his/her machine?