I am posting this so that other people can find it easily.
I just bought a Dell laptop, running Windows XP SP2. After installing the SBC Yahoo! DSL software, my computer would no longer boot. My machine would stop at the dreaded blue screen of death (BSOD), with the cryptic message, "STOP 0x0000007E".
Apparently, there is an incompatabilty between a piece of software that SBC's DSL package installs and the Dell Windows XP load. The problem software is Visual IP Insight, and specifically, the driver file IPVNMON.SYS.
To fix the problem, I booted into safe mode (hit F8 when Windows starts starting) command prompt. I renamed the file C:\Windows\system32\drivers\ipvnmon.sys to ipvnmon.sys.xxx.
Dell has an article on this subject, here. There is also a thread about it here.