Adobe Reader update wierd reboot

Last night I had an update available for Adobe reader(icon in the lower right corner by clock) .  I installed the update it asked for a reboot.  So I did.  On the restart before I got into windows 7 I got a black screen with a message prompt. From memory it said you may have an unauthorized copy of windows 7.  Click here to get a genuine copy / click here to ask me later / click here to close.   I x’d out and windows 7 started as normal I updated virus software and did full scans nothing came up.  It was just weird I have a genuine copy of windows7 64bit and I am sure the system knows it is.  Does this sound fishy…? Should I be worried about this?   

 

Thanks

 

Painbringer