here's the link
http://www-307.ibm.com/pc/support/si...id=MIGR-4JRMNE
i checked this thread but i cannot seem to find what specific A22 model you have.. so here's a link to the IBM website.
http://www-307.ibm.com/pc/support/si.../homeLenovo.do
just enter the required information (easy and straightforward) and it will bring you to the Download page.
you may need to have a floppy drive and 3 floppy diskettes to create diagnostic diskettes.
since it seems you have not tried to install SpeedFan or NHC to monitor your temps, we cannot really say if it is overheating.
also here's the link to the service manual.
ftp://ftp.software.ibm.com/pc/pccbbs...df/23p0896.pdf
you may need that if you want to open the laptop up to clean the insides or reapply the thermal compound (if it is overheating). the manual will also be your guide in finding locations of certain components like RAM or WiFi card.
as i said RUN PC DOCTOR. if all hardware checks out OK, then it could be Windows causing this random shutdown.