One of my users experienced this error. Our system builds remove the partition that the HP BIOS is searching for, your partitioning for dual boot could have similarly removed or changed the HP_Tools partition (I think that's the label of the parition their laptops ship with, uncertain).
The softpaq article that HP hosts as a solution to error 501 I that I found suggests flashing the bios. In my case it was sp62738, correpsonds with Elitebooks 8460p/w and 8560p as well as Probooks 6360b, 6460b, 6560b.
This was not however the solution. In every case I found that disabling the 'HP Quicklook' in the BIOS remedies the error on all of the machines that showed this error, all of them were EB8460p or 8560p models.
Quicklook appears to be a caching service for MS Outlook. Users who are aware of the feature can use it to rapidly access a pre-boot environment that hosts a copy of their emails/calendar/tasks/etc. Having never used it and forcing it disabled to allow my corporate users functionality of their laptops means I can't really speak on it's use but it's deployment certainly leaves something to be desired.
3Where do you see the error? – terdon – 2013-02-10T14:04:59.897
@terdon i saw it when i turned on my laptop, and when i restarted ubuntu, but now it disappeared! maybe i should ignore it – Lynob – 2013-02-10T15:01:14.097