I loose sound after closing lid to enter standby. A reboot always fixes the problem until I close lid and enter standby. If standby is disabled the problem does not occur.

Have checked all the usual places like device manager and sound settings in control panel - everything appears normal. Earphones always work.

Have installed latest sound drivers (Sigma Tel) from Dell with no change
Have reinstalled Direct X 9c - no change
ran SFC - found three indexes and deleted them still no sound after RESUMING from standby, everything else works great

Dxdiag generates the following:
Sound Tab 1: DirectSound test results: Failure at step 19 (User verification of software): HRESULT = 0x00000000 (error code) - this is only after resuming from standby mode. If tested before ENTERING standby, no errors are reported and no problems are reported.

System was restored to a known good point to no AVAIL. This point was immediately prior to letting windows update install 12 critical updates. Have reinstalled latest sound drivers (Sigma Tel) from Dell with no change.

Have deleted sound device from within device manager then reboot with new install. Everything works fine until resuming from standby mode. Also have latest BIOS from Dell. There are no tweaks for sound in BIOS.

Windows XP Home Edition (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_gdr.080814-1233)
Language: English (Regional Setting: English)
System Manufacturer: Dell Computer Corporation
System Model: Inspiron 5150
BIOS: Phoenix ROM BIOS PLUS VERSION 1.10 A38
Processor: Mobile Intel(R) Pentium(R) 4 CPU 2.66GHz
Memory: 1024MB RAM
Page File: 384MB used, 1040MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)

Any ideas?
Dell thinks the error message means the sound card is bad - I think they want to sell parts

Microsoft had me run MSCONFIG with no services other than M$ stuff and no startup programs but this didn't make any difference either. I haven't heard back yet