Messenger frags on reboot
 

I bought my HP Pavillion 533W - WinXP 1.2GHz system used and inherited the
previous owners registration info on it.
In my ignorance, I felt a need to remove his info and replace it with mine.
As such, after discovering no way to modify the existing system info, I
attempted to reload WinXP from a system disk over the existing version.

The result was:

1) a frag of my email POP address's on all my personal address's that
requires me to remove them and re enter them again any time the system shuts
off, and an error message that states "Windows Is Not Your default mail
program-Please run Messenger and select it..."
When It is in fact, listed as the default

2) a second boot OS choice at startup,

[boot loader]
timeout =30
default = multi(0)disk(0)rdisk(1)partition(2)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS = "Microsoft Windows XP Home
Edition"/Fastdetect/No-Execute=OptIn
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS = "Microsoft Windows XP Home
Edition"/Fastdetect

3) the system locks up and freezes on the WINDOWS IS SHUTTING DOWN screen
after requesting "reboot" and won't respond without a power down.
...................QUESTION.....................
Any idea how I fix this nusence problem???
SYSTEM RESTORE is not an option