Windows did not start successfully message-computer won't boot-HELP!!!

OK- My mom's computer-which is 1000 miles away from me came up with the "we are sorry for the inconvenience windows did not start successfully blah blah blah- computer won't load windows/boot in any of the choices given or start in any mode. Tried most of the advice found here and Microsoft etc.
I think(I know a dangerous thing!)rolleyes she could use the cd that came with the computer to reinstall or repair windows BUT she can't find them, called the mfgr-Emachines and they no longer carry the disks for a computer this old-7 yrs and offered NO help other than $199 for 3 months of technical NO SUPPORT!
Question - Does it have to be an OEM cd? Computer does not have a floppy drive in case we went that route to repair/reinstall windows etc.
Question - Can she use my upgrade copy of Windows Home Edition? She is running WIndows Home Ed.
Question - I saw something for sale on Ebay(I KNOW-usually bad idea!:-o) that says :Windows XP Home Installation CD (Drivers Optional)-Up for auction is one installation CD for Windows XP Home (32 bit) including Recovery Console. The CD does not come with a product key - this is ideal if you need to repair or format your computer and you lost or forgot to burn those important restore disks.
Question - will this work as a repair disk?
ANY information and help will be greatly appreciated and respected!
Also - could this be the hard drive?
At one point she did get some codes - like TR0028, CR080000011 etc - Is there a website that will tell me what the codes mean?
I am "shadetree" computer mechanic - I can fix simple things but and tenacious when it comes to finding a problem and trying to fix it.
Mom is of the mind that Windows has "turned" her computer off trying to get her to pay for tech support - could the windows updates actually have anything to do with this problem? How do you turn them off? are they necessary?
AM I over the quota with all my questions?:-o
BTW - I LOVE THIS SITE!!:major
Thanks in advance.
Paula
Her computer is and Emachine T2240 running Windows XP home edition.

 

Halo - THANK YOU!
We tried Last Know Good Config but it did not work - every option took us back to the same loop and screen - except disable restart on sys failure - it gave black screen with all the codes starting with TRAP 00000006-----------exception then TR=0028 CRO=800000011 CR2=00000000 CR3=00039000 and so on. I wrote down all the codes/info she read to me!:cry
I tried to help her get into BIOS/CMOS but was not sure on her computer - I think on mine it is f2 or f10 -
HOW do we get to the BIOS to change boot order?
Have asked around-no one has copy of OEM cd or any version of Win XP Home or Pro.
Emachines does not make it for this machine -too old:cry
She has not installed any new software, no lighting storms or power outages.
The reason she is convinced this is Microsoft(besides being old and senile-JUST KIDDING!) is because this happened right after the Windows automatic updates ran.
HOW can we turn those off - if we can fix this?
Again - THANK YOU for al of the great help and lighting fast response.
She is in a tizzy without her computer and driving me nuts - gotta love her though!!:-D
Paula

 

Thanks Plodr!
It is a T2240 Emachine.
I mailed her my upgrade copy of Windows XP Home. We will see if she can do a repair with it. I am going to check out the websiter you linked to HOWEVER - if you can locate disks somewhere to purchase you think would work I would greatly appreciate it! Again- THANK YOU for your advice and help!!

Paula

 

You guys(or girls - not sure which) are AWESOME!! I never dreamed or knew sites like this existed. Great advice and fast! It sets a girls heart to racing!
Seriously - THANK YOU! Hopefully she will get the CD tomorrow I sent down of my XP Home upgrade a- will post how it goes. If it does not work will try ordering one of the CD's for her model.

Paula