He says the PC suite software update and not N900 update..
@OT: Please choose ur words in the title carefully.. People get a mini Heart attack after reading such titles
That would be an update to the software updater. Now you have to reinstall the cable driver. The phone software has nothing to do with what has just happened - that was a pure system update to the NSU, which is why you have rebooted your PC - to allow for those changes.
Might have to remove PC Suite altogether and re-install. Cable driver is a funny thing, quite awkward....