On my Acer Aspire 4250 laptop my screen went black and a "Windows Error Recovery" message appears, it says "windows failed to start. A recent hardware or software change might be the cause" and when I tried the Startup Repair it wouldn’t work and I couldn’t reformat it either. How do I fix it without a disk?

After installing new updates I restarted my computer and I got a msg saying windows failed to start a recent hardware of software change might be the cause and it told me to put in my Windows Vista disc and "repair my computer" so I did. Then I got an error msg saying "The instruction at 0x73c7060 referenced memory at 0x000000000. THe memory could not be read" So now my computer doesn’t do a thing. THis is the second problem I have had with windows in the past three days. Do I need to buy a new computer?! What is the problem?! Any ideas!? I also tried reinstalling windows vista but it just said "To use the product Key you have entered, start the instalation from your existing version of windows" which I can’t do because WINDOWS FAILED TO START!

Thanks for any help anyone can give me

this morning i started up my computer and as soon as i was putting my password in it restarted it did it 2 times but the next 2 times it didn’t even get to the putting in password bit and after the 2 times it restarted it did it one more but before it did it went to windows error recovery and gave me options safe mode , safe mode with network, safe mode with comand ppromt , last know good config, and start windows normally and at the top it said (windows failed to start.a recent hardware or software change might be the cause tp fix the problem insert windows installati)on disk and restart the computer and chooser ur language and click next click repair your computer) i found the disk but it ain’t the actually windows vista disk its the computer company product recovery dvd=rom (pryon) and vista was pre installed i put the disk in and it dosent do nothing like it won’t run im trying to keep my programs on the computer any way to fix this problem or ideas or help
i already know what to do but the disk ain't running
help me plz its driving me insane i can't get the disk to run i tryed everything