Don't fiddle with the password side or anything during that portition as I figure you're guessing that's the cause.
Check the "start-up" side and verify just what gets loaded during this period and review what really needs to be there. If you've installed alot of s/w that's a good reason to clean things up. Further, you should also check the AV installed, like Norton or similar as these load as portions of this and that and they also take system resources and start to slow things down and/or become hogish. Use the system restore method to create "restore points" in order to have some return should anything get removed/deleted wrongly.
If you password is corrupt you would get very far, IMHO. You aslo should be seeing some eroor display or post suggesting a fix, etc.. If you haven't now, then generate recovery/restore discs, google for your HP model how its done. Also, Win7 provides that as well, do both, IMHO and label them. That way you're covered. Also, generate a "repair disc" again from Win7 side and allow that to do a repair. This is also found on Win7 install disc(if applicable) from menu display, repair console. good luck