Strange hard drive problem in Win XP SP2

I recently bought a new hard drive for my laptop. The HDD It's 250 GB, but XP SP2 only detects 128 GB of it when I check XP's partition manager.

'Oh great', I thought, 'now I need a BIOS update for an obsolete laptop in order to get 48 bit hard drive addressing, that's gonna be fun hunting down'. However, this was not the case, or rather, I'm pretty sure it isn't the case. I booted the laptop using an ubuntu live CD, and the partition manager there detected all 250 GBs. Furthermore, I put in a "PC Check" CD and booted from that to see if I could get any information out of that. the PC Check program booted nicely, and under the IDE controller information, it listed my new HDD, and detected all 250 GBs of it. Furthermore, it told me 48 bit addressing was supported, and enabled.

I then used Ubuntu to make a 200 GB partition, just to see if XP would accept it. I left it unpartitioned in Ubuntu, and rebooted into XP. Now, WinXP not only detected all of the new 200 GB partition, but it was also able to format it using the NTFS file system. However, everything wasn't prefect. As I was using my laptop with the 200GB partition mounted, several GBs of the free space would vanish into thin air, so to say, even though i never put anything at all onto it. Then, a few restarts later, the partition became unaccessible to XP, and it wanted to format it. I let it, but it failed to do so.

So my question is:
Do any of you know what could be wrong, and if you do, could you please tell me how to fix this problem?

Using Linux exclusively is not a valid option, because I frequently use software that isn't possible to run using WINE, and doesn't have a Linux equivalent.

The system configuration is roughly this:
Brand/model: Acer Travelmate 4500
Chipset: Intel 855 GM or GME
CPU: Pentium M @ 1.6GHz
Hard disk: 250 GB Western Digital Scorpio, IDE P-ATA interface
Operating system: Windows XP SP2 (atapi.sys checked to be of a later version than the minimum to support 48bit LSA)

Oh yeah, I also tried two different WinXP downloads. One corporate ed, and one OEM where I could use the product key at the back of my laptop. Same results in both.

Strange, normally it's XP with no service packs that has the 128 GB limit - anything newer is supposed to have this limitation fixed :p

Only thing I can think of right now is a corrupt/bad partition table which XP is trying to use - wipe the entire thing from linux (not just delete partitions), and create a new partition table. Maybe create a small ntfs partition whilst in linux (you don't need to bother format it, just set the partition type appropriately) and partition the rest of the disk how you like, then try installing XP into that ntfs one.