Linux Mint doesn't always boot

[Giraffemonster]

I've been using Linux Mint 12 (Lisa) 64-bit for around three days now. From the start of my installation, I've been having some troubles with booting my system. I get the motherboard BIOS splash-screen (Not sure what it's actually called), and then it boots. If I've done a hard restart because of a crash or something, it doesn't directly boot, but leads me to the GRUB bootloader. I select my default OS choice, Linux Mint 12 normally, and sometimes it works, sometimes it doesn't.

After I select which operating system to use, I get a black screen with a gray underscore that flashes as if it's in a terminal session. If it works, my monitor sleeps for a few seconds (Light goes from green to orange) and then turns back on, along with the operating system. Sometimes though, it just stays at the underscore. I have to restart and try again if that's the case.

I'm very new to this, as this is my first time trying Linux Mint, the first time I've installed a processor, and the first 64-bit operating system I've used. If you need any more information, I'll be sure to provide you with it. I'd just like some help with the issue. I have reinstalled the OS, this problem was there before.

System specs in case they're necessary:
- AMD A8-3850 2.9Ghz APU (Radeon 6550D integrated graphics)
- Biostar TA75M Motherboard
- 2x4GB G. Skill Ripjaws 1600Mhz DDR3
- Mushkin 60GB SSD SATA III

Also, a different but still boot-related problem. Sometimes when I start Linux Mint up after a crash or something, I end up in GNOME Classic, but with all the "old-school" icons and such. The file manager looks different, etc. It's an easy fix, as I just log out and log back in under GNOME Classic where everything's fine. I'd still like to know if there's anything I could find out concerning that. Thanks.

[Tuxi]

Hi!, first of all:
Had you tested the integrity of the LinuxMint CD/DVD you used (cheksum md5)? if the dvd not pass the cheksum md5 linux will crash frequently or unable to boot.
Had you analize your HD integrity ? (scandisk for win,fdisk, etcc).

Another cuestion is your AMD onboard graphical chipset is capable of running well on LM12 (i have read that some AMD/ATI chipsets have serious problems running Linux Mint with GNOME3), but i think it is not relation to the non-booting.

Note: i relative newbie on linux world, but i think that boots problems is by an defective installation.

PD: prove run linux on recovery mode, or via the liveLM.