need help with my acer aspire 5738 64 bit

ok this is my problem. i bought a used laptop from a pawn shop i didnt want anything fancy i just wanted a cheap laptop that could do a few things until i can afford to buy a brandnew one with all the wingdings. Ive had this laptop for about 7 months. i used to have a overheating problem where my laptop would shutoff by itself but it didnt start doing that until installed a few updates. its weird because after i would do a system restore you know back to a date before i installed it would stop shutting off. so i turned windows updates off completely for a week. . i did some research and found that my model had a known problem of this and in order to be fixed i would have to update the bios.i am very computer illiterate. i didnt know what to do. sooo i keep my computer cooler etc. all of a sudden out the blue my computer stop shutting off. it was still getting very hot but it wouldnt shut off by itself. i was finally able to turn back on windows updates fully update my computer and everything was going fine until bam 2 weeks ago i was removing a virus off of my computer it asked me to restart my computer i did. when i did that it stopped working. all i would get is a black screen with a blinking dash in the upper left corner. i did some research found out how to start my computer in safe mode removed the virus using super antispyware program did a system restore and it started back working again. i cant exactly remember what made me do this but i downloaded the updated bios and ran it. it restarted and now im on it.

its so long because i am really a dummy when it comes to computer stuff. but i am a fast learner if you can explain.i want to give as much background info so you have an idea about what im talking about.

my question is WTF is going on with this thing
how to i fix it or get it fixed
how will i know that running the new bios worked
what can i do to prevent these problems

here is my basic system info

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit
Processor: Intel(R) Core(TM)2 Duo CPU T6600 @ 2.20GHz, Intel64 Family 6 Model 23 Stepping 10
Processor Count: 2
RAM: 4090 Mb
Graphics Card: ATI Mobility Radeon HD 4500 Series, 512 Mb
Hard Drives: C: Total - 305142 MB, Free - 107613 MB;
Motherboard: Acer, JV50
Antivirus: avast! Antivirus, Updated and Enabled


any help would be really greatly appreciated

pleasse and thanks