acer aspire starts very slow, takes about 30 minutes to show password box

the bios gets opened with F2 and also the process with the F9 and F10 but again the same problem restarts.

once it showed the UUID error. also nest time it showed that there are errors so it tried itself to find out and finaly showed 0xc000021a error. next time it diagnosed the errors and then showed "repairing disk errors. it may take over an hour to complete". after that it took 4-5 hours to complete and later started the pc faster than before but after entering the password it failed to load desktop and showed black screen and lastly the same problem again.

Please help me!!!

The first thing you can try is executing a disk check utility from a live cd (or attaching your hard disk to another computer).

I don't think that it's some file corruction problem, but you can also try to re-install windows.

The last thing /and I hope you won't need it/ is that your disk is faulty and you have to change it