A) you generally get an icon to make your own cd somewhere in the recovery tools (start menu or a certain key at boot). If not, using the same tools, you can generally recover from a hidden partition. Also you can order CDs from the manufacturer

B) is it xp or vista?

Under XP go to control panel -> system -> advanced tab -> startup and recovery button. Uncheck automatically restart. Then when it BSODs, write down the error number (something like 0x-whatever). Google it.

c) Winlogon may be corrupted. On both XP and vista you can check by going to run and typing "sfc /scannow". Leave it for a while until its done, then reboot.

d) buffer overrun errors generally get patched in hotfixes, updqates and service packs. Search the microsoft websites and check for updates from within windows. Make sure you have SP3 if you run xp, and SP1 if you run vista.

e) after looking into these, report back.