Problem with laptop installation

[NATHAN]

Hi , I got a funny problem with my 2nd comp (laptop). I have hoster latest version on my desktop pc working fine , yesterday i hooked my laptop up to the net and upgraded the hoster on there. All was working fine till i got to my gig in the evening and switched on the laptop ,went to boot hoster and it said something like ( Serial number does not match) and it would not work. Only way i got round it for the night was to do a system restore to last weeks date. Can you tell me what could have caused it to go wrong????

thanks nath.