Computer Freezes Every Day - Help Needed

[1MoreFish4U]

Start off by saying I am not real computer savvy. The problem unit is about 4 years old & my daughter uses it mostly for surfing kids sites. She's 5. The computer freezes up when it remains inactive for many hours or overnight. This has been happening every day for several weeks. AdAware & AVG find no problems. Here is the System Info if it helps. When the freeze occurs the only way out is a hard reboot. I have tried ctrol+alt+del; and esc with no success. Any suggestions? Thanks in advance.

OS Name Microsoft Windows XP Home Edition
Version 5.1.2600 Service Pack 2 Build 2600
OS Manufacturer Microsoft Corporation
System Name CARLY
System Manufacturer Dell Computer Corporation
System Model Dimension 2300
System Type X86-based PC
Processor x86 Family 15 Model 1 Stepping 3 GenuineIntel ~1794 Mhz
BIOS Version/Date Mitac Corp A02, 08/26/2002
SMBIOS Version 2.3
Windows Directory C:\WINDOWS
System Directory C:\WINDOWS\system32
Boot Device \Device\HarddiskVolume2
Locale United States
Hardware Abstraction Layer Version = "5.1.2600.2180 (xpsp_sp2_rtm.040803-2158)"
User Name CARLY\Dave
Time Zone Eastern Daylight Time
Total Physical Memory 1,024.00 MB
Available Physical Memory 636.36 MB
Total Virtual Memory 2.00 GB
Available Virtual Memory 1.96 GB
Page File Space 1.09 GB
Page File C:\pagefile.sys