Dual boot Win2000 with win98

After hardware installation of modem, and network card, and sound card. Win 98 was loaded without a problem. All devices were found and appropriate drivers were loaded. Then Win2000 Pro was loaded and all went well also.

Customer did something that was unknown. Hard drive was low level formated, with appropriate somftware from manufactruer. Win 98 was reloaded successfully. Then Win2000 Pro was loaded. Now the system freezes when Win 2000 Pro states “System checking hardware”. Nothing happens after that.

What could be the problem(s)???