My Gateway E-4200 is not booting properly - Gateway e-4200 P2 400MHz Tower (2048272368) PC Desktop

first thing I would do is boot to safe mode by pressing f8 at the gateway screen to make sure the drive is working properly. do a virus and malware scan reboot see if it boot normally

yes, you can boot into "safe mode" by holding down the proper function key when booting up. Different mfrs use different function "F" keys to do this. Look up Gateway on line to determine which key it is for yours. Always chose "Safe mode with Networking." Go to MY COMPUTER and highlight you harddisk and choose "TOOLS". Let the tool scan your disk and repair all the errors for you by ticking the proper blocks. Takes awhile, be patient.

reset BIOS to original default rules, and then start

The most common reason a computer won't start can be a piece of hardware has failed or is causing a problem but that hardware isn't usually a hard drive, the part of your computer that stores all of your files. To fix such kinds of issue, you can take the following steps.1.create a bootable usb or cd ,there are kinds of software for you to complete this step, you can choose Fix Boot,EasyBootDisk or Windows Boot Genius. I suggest you to use Windows Boot Genius, it is easier and more effective.2.boot your computer from the created disk3.fix the issue after run the softwareBy the way, before any further steps you should make sure the power supply is good. Any hardware issues such as pc power and cable,motherboard corrupted should be troubleshooted.I don't suggest you to try the solution above until you are sure there is nothing to do with the hardware.
source:http://windows-8-password-recovery.com/computer-wont-boot.html

The motherboard - the southbridge chip has failed. You must replace the motherboard.

First check your power supply section and check your power fan that is running properly. if ok then the suspected area is your processor section. please check it if its collar fan nor running properly then clean up or change that. and the other advice is please check your processor pin which are too tiny. be careful about these.

connect your router to computer with ethernet cable.

Then go to start menu then type in run 'ipconfig /all"

you find ip adreses sub net and GATEWAY.
GATEWAY ip is your router ip.

Let me know if you need more assistanse.
Thanks.

The beeps are usually an error code meaning either the RAM or video card has went bad or are not properly seated. Leaving it out as you did could have caused the parts to come unseated when you moved the unit. Try reseating the RAM & video card and then retry booting. Hope this helps & please remember to rate my answer. Thanks.

Try running McAfee virus scan or Norton virus scan. One of those programs should identify and remove the virus for you. Hope this helps.

512MB Module 512MB-533MHz DDR2-533 PC2-4200, 200p SODIMM, 1.8v 1GB Module 1024MB-533MHz DDR2-533 PC2-4200, 200p SODIMM, 1.8v So you need DDR2-533 PC2-4200 200P SODIMM'S
1.8 Volts