My screen's display is all messed and shaky, HELP!

It was working perfectly until I restarted it yesterday by the morning. I started to get this bunch-load of horizontal lines moving up and down, side to side. I followed that instruction of changing the "Screen Refresh Rate" but it didn't work. Disconnected the PC and cleaned everything inside, even the graphic memory, all the motherboard, the fans, etc. I also checked the VGA cables and they work just work fine. The monitor have no issues either. I also tried removing the Monitor controllers and graphic memory's drivers. Installed the recommended drivers by ATI and I still get the same problem.

Can someone please tell me what else can I do?

PC's specs:
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System Information
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Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp.080413-2111)
Language: Spanish (Regional Setting: English)
System Manufacturer: Compaq Presario 061
System Model: EG733AA-ABA SR1620NX NA540
BIOS: Phoenix - Award BIOS v6.00PG
Processor: AMD Sempron(tm) Processor 3400+, MMX, 3DNow, ~2.0GHz
Memory: 1982MB RAM
Page File: 877MB used, 3001MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
DxDiag Version: 5.03.2600.5512 32bit Unicode

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Display Devices
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Card name: ATI RADEON XPRESS 200 Series
Manufacturer: ATI Technologies Inc.
Chip type: ATI Radeon Xpress Series (0x5954)
DAC type: Internal DAC(400MHz)
Device Key: Enum\PCI\VEN_1002&DEV_5954&SUBSYS_2A24103C&REV_00
Display Memory: 256.0 MB
Current Mode: 1024 x 768 (32 bit) (75Hz)
Monitor: Monitor Plug and Play
Monitor Max Res: 1600,1200
Driver Name: ati2dvag.dll
Driver Version: 6.14.0010.6925 (English)
DDI Version: 9 (or higher)
Driver Attributes: Final Retail
Driver Date/Size: 2/10/2010 21:45:14, 325120 bytes