For the past two days my computer has been randomly freezing. When it happens, the keyboard and mouse become unresponsive and the display becomes frozen, continually displaying whatever was on screen at the time. If any sound is playing at the time it freezes, then a single, continuous tone plays from the speakers. It occured three times yesterday and so far five times today. The last time it happened, I left my computer on for ten minutes and it still remained frozen, so I was forced to hold down the power button to turn it off (as I had to do with all the other times). I have no problems during start up, except each time I start up after it's frozen, it'll tell me Windows did not shut down properly (because I was forced to manually turn it off) and prompts if I'd like to start normally or in safe mode. After start up, it may freeze within five minutes, or may not freeze at all for several hours. Each time it's occured I've been doing something different; a couple of times I was browsing the internet, listening to music or watching a movie with Windows Media Player, once it happened while I was typing in Microsoft Excel (nothing else was running), another time it occured when I was only watching a movie in WMP. Just before the freezing occured, I moved the computer from one house to another, so something could have occured during the two hour drive, or while I was taking it apart/setting it up, but I was very careful and don't feel this is the case. Before the move, it was working completely fine. Since moving, the only new things I've added/done to the PC is connect a printer, and change my internet connection from a wired connection to a USB wireless modem (new house doesn't have a phone line). I tried a system restore, rolling back all my settings to a couple of weeks ago, before the move when everything was working. However, 15 minutes after doing so, it froze again. Additionally, a couple of the times it has frozen have occured while the printer and wireless USB modem have not been connected. I took the temperature using SpeedFan during one freeze, and it never rose above 60 degrees celcius (58 was the maximum). The internals have been recently cleaned for dust. I ran a virus scan with AVG Free (the most recent version and definitions) and my computer was clean. The computer is two to three years old, and it has had problems before. (A few months ago I was getting random shut downs, which ceased once I replaced the hard drive with a new one and removed (what i think was) a faulty stick of ram.) I can't really afford to buy a new computer, and I need it for university/work, so I'm really hoping someone knows something I can do to fix this problem. My specifications are below, let me know if you need any more details. Model: Compaq SR5240AN OS: Windows 7 Professional 64-bit edition Motherboard: MCP61PM-HM PSU: 250 W Max (No UPS) CPU: AMD Athlon 64 X2 Dual Core Processor 4600+ 2.40 GHz GPU: NVIDIA GeForce 6150SE nForce 430 RAM: 3.00 GB (2.87 GB usable) RamBo DDR2 (3 x 1.00 GB sticks) HDD: WDC WD10 01FALS-00J7B SCSI Disk Device Thank you in advance for reading through this and helping me out.