Pc Recognized Differently Everytime

I use sky player online, and anybody who has used it before will know that it registers your pc as the main registered computer and you can change this once a month.

Anyway, everytime I log on to sky player, it is recognising my pc as a different pc, for example first time I log on it'll recognise my pc as PC1 then the next time it will be PC2 etc, meaning that within 2 log ins I've reached the maximum changes per month and can no longer use sky player.

It seems to be a setting with pc somewhere rather than sky player as its the same when I log on to my alliance-leicester internet banking. The log on uses a username and password as standard but also asks an additional security question when it recognises you've logged on from a new unfamiliar pc, but its asking me this security question everytime I log on meaning its not recognising my pc as being the same as I used the last time.

I have 02 broadband, windows 7 32bit and am using a netgear router.