Thanks for the comments. I will try a few things. I've updated the drivers, but that didn't help.
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System Information
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Time of this report: 12/13/2011, 21:08:50
Operating System: Windows 7 Home Premium 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.110622-1506)
Language: English (Regional Setting: English)
System Manufacturer: Hewlett-Packard
System Model: HPE-450t
BIOS: 07/12/10 14:03:04 Ver: 6.12
Processor: Intel® Core i7 CPU 870 @ 2.93GHz (8 CPUs), ~2.9GHz
Memory: 8192MB RAM
Available OS Memory: 8152MB RAM
Page File: 4255MB used, 12044MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: 96 DPI (100 percent)
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7601.17514 32bit Unicode
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Display Devices
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Card name: ATI Radeon HD 5450
Manufacturer: Advanced Micro Devices, Inc.
Chip type: ATI display adapter (0x68F9)
DAC type: Internal DAC(400MHz)
Device Key: Enum\PCI\VEN_1002&DEV_68F9&SUBSYS_21301462&REV_00
Display Memory: 733 MB
Dedicated Memory: 1010 MB
Shared Memory: 3819 MB
Current Mode: 1920 x 1080 (32 bit) (60Hz)
Monitor Name: Acer G235H
Monitor Model: P235H
Monitor Id: ACR00CB
Native Mode: 1920 x 1080(p) (59.934Hz)
Output Type: HDMI
Driver File Version: 8.17.0010.1094 (English)
Driver Version: 8.892.1.1000
DDI Version: 11
Driver Model: WDDM 1.1
Driver Attributes: Final Retail
Driver Date/Size: 10/24/2011 05:19:12, 862720 bytes