I have a Gateway laptop 9300 solo series that has a very wierd temper. When i have the external power supply hooked up the computer it will lock up so I turned it off. On power up the Gateway logo will come up and then beep which is normal then it should go in the windows start up but it dosent it stays on the gateway logo. Know if I power up on battery only it WILL work great normal operations and if I plug in the power supply again it will lock up.
(ACTION TAKEN)-I replaced the extrnal power supply with no results, I've powered up with no battery and AC only with no results and last I've reformatted the hard drive in case on software issues but guess what same thing now what and PLEASE HELP. (One last thought could the electronics in the hard drive be down which relies on transformer power again batt. power makes it work great.)

simple answer, dont buy a gateway!!!lol, yeah the hard dirve is probably bad, but it really could be anything on the inside of your laptop, there is no sure way to tell unless you open it up.

If you have dropped the external power supply hard enough or it has alot of collisions over time the external power supply may be broken inside and might be shorting your computer out. Yes its an extremely thin thought but... Ive seen things that would scare most people. lol

Yes you may have broken that parts you said but i think the problem is occurring around the power connector on the laptop or the component that signals the battery to switch over to ac. you should check your Mother Board for flaws.

Thank you very much for take your time to help, But I thought the same thing and I found with two other working power supplies that it does the same thing whats odd is that it runs on phoenix bios and it doesnt give me any error codes to indicate a bad mother board.