SP3 Installation Repair Failure

I purchased the Dell Inspiron 1525 laptop about 2 years ago. It shipped with Vista at the time, but I installed XP on the partition Vista was installed on and have been using it happily ever since. There is a common problem as it turns out, after having read through other forums, that used to exist with Dell laptops, including mine and that is that they would come shipped with the Mediadirect button. When pressed, it supposedly boots the laptop to another partition, which would start up a multimedia software that can playback CDs, DVDs and/or other media files on the accessible storage. The critical and serious issue is that once this button is pressed and you try to turn on the laptop normally again (boot into Windows), it would not boot up, producing the Invalid partition table error at boot-up, suggesting that the former process messes up the boot record somehow.

The same thing happened to me before. A quick suggested fix was to press the button again. While it didn't solve the issue, it at least booted in the right partition, but complained about an ntfs sys file not being there. I solved this myself by repairing the existing Win XP Pro SP3 installation via an XP SP2 CD, which reverted back SP3 to SP2 without much hassle, surprisingly, and Windows booted up normally. I just had to manually update the system to SP3 again using Windows update and that was all. Other software like IE and WMP were also reverted, but reinstalled to the latest version manually.