Two little problems I can't figure out

Note that I'm not super intelligent with computers, so try to keep it basic.

Okay, I use my older brother's computer because I'm currently saving up money for my own. His computer will often freeze up doing simple things such as browsing/using the internet (Mozilla Firefox.) I don't understand why it's suddenly doing this, it just started and I've been using this computer for about two years. No changes that would make it do that because it's got all the same hardware.

Another thing is that the Monitor will go to sleep randomly and then won't get any signal from the computer til' you restart it. I don't even know where to start with this one.

Computer Summary; Everest Home Edition:

--------[ Summary ]-----------------------------------------------------------------------------------------------------

Computer:
Operating System Microsoft Windows XP Media Center Edition
OS Service Pack Service Pack 2
DirectX 4.09.00.0904 (DirectX 9.0c)
Computer Name ZANE
User Name HP_Administrator

Motherboard:
CPU Type DualCore AMD Athlon 64 X2, 2000 MHz (10 x 200) 3800+
Motherboard Name MSI RS482M2/RX482M2 (MS-7093) (3 PCI, 1 PCI-E x16, 4 DDR DIMM, Audio, Video, LAN, IEEE-1394)
Motherboard Chipset ATI Radeon Xpress 200, AMD Hammer
System Memory 1024 MB (PC3200 DDR SDRAM)
BIOS Type Award (01/12/06)
Communication Port ECP Printer Port (LPT1)

Display:
Video Adapter NVIDIA GeForce 7600 GS (512 MB)
Monitor HP w2007 Wide LCD Monitor [NoDB] (CNN727415P)

Multimedia:
Audio Adapter ATI SB400 - AC'97 Audio Controller

Storage:
IDE Controller Standard Dual Channel PCI IDE Controller
IDE Controller Standard Dual Channel PCI IDE Controller
Disk Drive ST3250823AS (250 GB, 7200 RPM, SATA)
Disk Drive Generic USB SD Reader USB Device
Disk Drive Generic USB CF Reader USB Device
Disk Drive Generic USB SM Reader USB Device
Disk Drive Generic USB MS Reader USB Device
Optical Drive HP DVD Writer 840b
Optical Drive IDE-DVD DROM6216
SMART Hard Disks Status OK

Partitions:
C: (NTFS) 229753 MB (170695 MB free)
D: (FAT32) 8703 MB (1149 MB free)
Total Size 232.9 GB (167.8 GB free)

Input:
Keyboard Enhanced Mulmedia PS/2 Keyboard
Keyboard Microsoft eHome MCIR 109 Keyboard
Keyboard Microsoft eHome MCIR Keyboard
Keyboard Microsoft eHome Remote Control Keyboard keys
Mouse HID-compliant mouse
Mouse PS/2 Compatible Mouse

Network:
Network Adapter NETGEAR WG111v2 54Mbps Wireless USB 2.0 Adapter (192.168.0.10)
Modem Agere Systems PCI-SV92PP Soft Modem

Peripherals:
Printer Fax
Printer Microsoft Office Document Image Writer
Printer Quicken PDF Printer
USB1 Controller ATI SB400 - USB Controller
USB1 Controller ATI SB400 - USB Controller
USB2 Controller ATI SB400 - USB 2.0 Controller
USB Device eHome Infrared Receiver
USB Device NETGEAR WG111v2 54Mbps Wireless USB 2.0 Adapter
USB Device USB Mass Storage Device

Probably the Ram failing (System Memory 1024 MB (PC3200 DDR SDRAM))
You could download and run Memtest (create the bootable Memtest Disk) and test your Ram for 7 Passes (or basically 4 Hrs minimum)

And you could check for any updated drivers for Your Computer