Sound scratchy or nonexistent (please help!)

[krasers]

One day I turned on my computer and it would play almost no sounds... a few basic ones come out scratchy. According to device manager I have no problems... taking advice from another thread I downloaded and installed the Intel Mobile Chipset driver from dell's website and then uninstalled my sound drivers and installed the Sigmatel sound driver also from dell... still have the same problem. Any help would be greatly appreciated...here are my system specs:

Product : Inspiron 5150
Serial Number : 9HWVC51
Unique ID : 44454C4C-48001057-8056B9C0-4F433531
SKU : Unspecified
Family : Unspecified
Start mode : Power Switch
OEM #1 : Dell System
OEM #2 : 5[0003]

Mainboard:
Manufacturer : Dell Computer Corporation
Product : 0W0940
Version : Unspecified
Serial Number : .9HWVC51.CN1296146L7219.
Support MP : No

Chassis Information :
Manufacturer : Dell Computer Corporation
Type : Notebook
Version : Unspecified
Serial Number : 9HWVC51
Asset : Unspecified

On-Board Device Information :
Device : NVIDIA GeForceFX5200 (Video)
Device : Sigmatel 9750 (Sound)
Embedded Controller : No

Processor:
General Information :
Type : Intel Pentium 4
Internal Specification : Mobile Intel(R) Pentium(R) 4 CPU 2.80GHz Codename : Northwood
Revision : D1
Technology : 0.13µ
CPU ID : F.2.9
CPU IDEx : F.2.9
Brand ID : 8
Microcode : MU0F2923
Number of Logical Processors : 2
Mobile : Yes

Bios :
Manufacturer : Dell Computer Corporation
Version : A34
Date : 05/26/2004 (mm/dd/yyyy)
Address : 0x0 on (byte=) KB
Copyright : Copyright (C) 1985-1988 Phoenix Technologies Ltd. DMI Version : 2.3

Chipset:
General Information :
NorthBridge : Intel i85xGM
SouthBridge : 82801DBM (ICH4-M) LPC Interface Bridge

NorthBridge Information :
Architecture : HUB
Manufacturer : Intel (Dell Computer Corp)
Codename : Montara
Revision : A2
Bus Speed : 132.9 MHz FSB
Frequency : 531.5 MHz (QDR)
FSB max. Support : 400 MHz
RAM max. Support : DDR (266 MHz)

Memory Information :
DIMM_A ( ) : 256 MB - DIMM
Type : DDR-SDRAM PC2100
Frequency : 132.9 MHz
DRAM/FSB Ratio : 1/1
Supported Channels : Dual (128-bit)
ECC Diagnostic : No

[Disk_Contented]

Try headphones in the output socket.

[krasers]

Same problem using headphones so I figure there is no problem with my speakers... can't figure out what to download to fix this though...