If you not already seen this: http://www.debian.org/releases/stable/i386/release-notes/ch-information.en.html#s-hp-acpi
Thanks a lot. I found that bug report after I had submitted my query. I would like to know whether compiling a pristine kernel 2.6.19 would not break IPtables, because I think the IPTables package in Debian requires certain kernel patches not found in the official sources. Regards.