Lenovo T420 & T520 datasheet here --> http://shop.lenovo.com/us/ww/pdf/t420_t … asheet.pdf
I note that this model may have a TPM & SSD (SerialATA),  Intel®    Integrated    HD Graphics, & QM67 Chipset.
Could you post your HWID's if possible steje?

On a separate note, if this model supports dual-channel memory, you may find better performance using identical pairs of SO-DIMM's.

I found a thread concerning the previous laptop model (T410)... which I "also" have as the "loaner" prior to rec'ving the T420; and I have the same BSOD issue as the OP in that thread on BOTH the 410 and the 420. In my situation, I hadn't modified the driver pack or tried to slip in any specific drivers myself - from a "driver" perspective, it's a "clean source" as suggested by Overflow.

So I'm guessing that in both the T410 and T420 cases, it is likely a chipset and/or ssd issue (though other folks seem to be of the opinion that the bios settings for the ssd should allow XP to recognize the drive without explicit drivers - which I'll buy).

At any rate - any results from the community with the T420 w/ssd...? If you've got it working, share any steps to make it so? I'm going to go back to a completely fresh un-modified UBCD4win 3.60 and re-test in the meantime (but really, my standard build is just "application" mods, not driver stuff).