If you have the latest Flash Player 188.8.131.52 installed, then most likely that "update notification" is a fake (malware). Can you post a screenshot of it?
That site has nothing to do with Adobe! Download Flash Player only from Adobe.com or Macromedia.com
If you get pop-ups leading to that site, then you need to check your system for malware.
I did a WHOIS on that domain softwarecentr.com: it's registered by a Russian company!
This sounds a lot like The Moon worm:
It affected (and continues to affect) a lot of older home routers. If you haven't updated your router's firmware recently, I'd recommend power-cycling the router (this should clear out the worm temporarily), then updating the router's firmware following the manufacturer's instructions.
If you installed software based on the prompts you saw, you probably installed malware on your machine and not an authentic Flash Player distributable. That's problematic. Depending on your level of paranoia, your options range from running some AntiVirus/AntiMalware stuff to just blowing everything away and reinstalling from scratch. If it was my personal machine, I would do the latter.
Anyway, sorry you got tricked by this. Flash Player is super popular (98% of internet-connected computers have it), so it's a good target for malware developers that want to pretend to be something legitimate that everyone needs.
Also, if you have a machine that you haven't compromised, I would recommend doing the router updates and anything else on that one, until you deal with the malware infection on the other. Better to be safe than sorry in that regard.
Finally, always download software from the vendor's website. Don't click though on links or emails to update installers unless you're 100% sure that they're legit. For Flash Player, you can always go to http://get.adobe.com/flashplayer to get the latest update.