HDD Issue

To start I'd like to say that returning the drive isn't possible as I've had it for far too long. Anyway I have this HDD here: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Installed it, formatted it, and installed windows 7 on it. Shortly after BIOS, the load would freeze at the screen with the flashing underscore. I changed some boot settings around and it would finally load. Anyhow later on I decided to make a backup and noticed that Acronis was identifying the drive as a GPT. On top of that event viewer for the longest time has been getting a warning almost every 5 minutes that read: "The system failed to flush data to the transaction log. Corruption may occur."

1. What is GPT and how do I change it to MBR if it is possible?
2. What could be causing this error?

If you need any other info from me just let me know, and I thank anyone for the help in advance.