Creative's AutoUpdater (for soundcard drivers, etc) modifies the IE8 UserAgent (I have NFI why Creative thinks they are important enough to warrant this).

The modified user agent is: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; Tablet PC 2.0; Creative AutoUpdate v1.40.01)

This matches the "pda" substring in the mobile_fu regex, resulting in IE8 users with Creative soundcards being served a mobile version of the site.

This could be solved by changing the "pda" to "\bpda", to check that the string "PDA" is preceded by a word boundary, rather than being a substring.