SPDIF stopped working

Hi. I have an HP Pavilion desktop a1520n pc. I have realtek hd sound card. I got for Christmas Logitech Z-5500 Surround speakers. I hooked it up to my PC with coax cable to the SPDIF setting. WOW! Great sound. In the Logitech control center when I played a DTS audio CD it would show in the information window "DTS". When I played a DVD with surround the control panel would show either Dolby 5.1, or DTS, or whatever sound setup I used. I play both the DVD's and DTS CDs with Power DVD 7 Deluxe. I have the Realtek control setup for SPDIF 5.1, I have Power DVD 7 setup for SPDIF. Everything was great. In Power DVD 7 while playing a DVD or CD, you can click on the info tab and it would show output Realtek HD audio SPDIF.
Last week I udated the Realtek sound card driver. I guess I should have left well enough alone. I still get sound through the SPDIF but not real surround or DTS. The Logitech control does not display DTS or 5.1 anymore. When I play a DVD in 5.1 or DTS I don't get any dialouge in the center speaker. Power DVD 7 info box says output Realtek HD audio direct rear. SPDIF not in use. Yet I am using SPDIF and getting audio but not true surround or DTS.
I tried rolling back the drivers. Nope. Same problem. I tried System Restore. Nope. I tried uninstalling and re installing Power DVD 7. Nope. After this problem started Realtek came out with another update to the driver. I updated to the newest driver 5.10.0.5559 Nope. I tried re installing the original drivers I found at HP. Nope. I called Logitech. They said it a driver issue and to contact Realtek. I contacted Realtek with no response. I have since re-installed the newest drivers, but I have still lost the surround and DTS through the SPDIF.
Any thoughts or ideas appreciated. Oh, I'm running XP Media Center edition.
Thanks

 

I was up until 3am working on this trying different things. I got it back for now. I hope it stays working. Here is what I did to finally get it to work right.

I went to control panel, clicked add/remove. I uninstalled Realtek High Definition. I did not restart Windows. I uninstalled kb888111. I did not restart Windows. I went into the registry with regedit. I navigated to HKEY LOCAL MACHINE/SOFTWARE/MICROSOFT/UPDATES/WINDOWS XP/SP3/KB888111
I deleted KB888111 and closed the registry.

I then installed the newest driver from Realtek. I then restarted Windows and, for now anyway, SPDIF is again working properly.