Hello Yossi_sabto,
Welcome to the HP Forums! I hope you enjoy your experience!
I understand you are experiencing driver conflicts since upgrading to Windows 8.1. Unfortunately, this computer only has Windows Vista drivers as indicated here: HP Pavilion dv2500 CTO Notebook PC Drivers
My recommendation is to return the computer to Windows Vista. This would allow you to reinstall the correct drivers. Please let me know if you have any other questions or concerns.
Thanks for choosing the HP Forums. Have a great day!
Mario
