|"complete crash -- unable to reboot"|
What do you mean when you say that ?
If the computer is not booting normally - if you DO NOT see video while booting before Windows loads, even if Windows itself won't load from the hard drive - the most common thing that causes an emachines desktop system to fail to boot is it's BESTEC power supply is failing or is dead.
emachines desktop computers usually have a BESTEC power supply.
BESTEC power supplies have a reputation of malfunctioning and failing a lot more often than average, and when they do that, they are a lot more likely than average to damage something else, especially when they fail completely, often the mboard.
A BESTEC power supply malfunctioning or failing is probably the NUMBER ONE REASON an emachines desktop system fails to boot normally !
If you DO have a BESTEC power supply, that's probably what is causing your problem.
If you remove it before it gets any worse and try a known good power supply with the system, if you are fortunate and the BESTEC power supply hasn't already damaged the mboard, the system will work fine.
If it is failing, you can usually replace it with any decent quality standard sized standard ATX PS with the same capacity or greater.
Standard (PS/2) power supply size - 86mm high, 150mm wide, 140mm deep, or 3 3/8" h x 5 7/8" w x 5 1/2" d , or very close to that, though the depth can be more or less for some PSs.
Don't buy an el-cheapo (in quality) PS.
See response 3 in this:
Note - I may have mentioned Coolermaster in that - I have recently found some models have only a 1 year warranty, some are known to have premature fan failures, some are known to develop failing electrolytic capacitors.
Check for Recovery disk availability -
Accessories - Purchase Accessories, eRecovery CDs....
If a disk or set of disks is available, it's usually MUCH cheaper to buy including shipping than buying merely the cheapest type of XP CD available - an OEM XP Home CD.