Microsoft Kernel Wave Audio Mixer keeps unolading

[tony_o]

On a laptop, Acer TravelMate 4650, under WIN XP Pro, with the Realtek AC'97 Audio (where the Realtek Audio driver is 5.10.0.5890 of 22 July 2005),

the Microsoft Kernel Wave Audio Mixer keeps unloading. Its driver is kmixer.sys, version 5.1.2535.0

First of all, after booting it is usually not loaded. After installing its driver manually (right-clicking on the inf file), it is there (meaning visible in the Device Manager with "Show hidden devices" activated), but disappears after some time, which varies from a few seconds to a few hours (I have not ben able to track any pattern of when or why it is unloaded; but it seems not to get unloaded so quickly when the machine is operated on battery). If I "catch it in time" and reload it (sometimes right-clicking the inf file works, sometimes it does not and the driver is only reloaded after simply disabling and re-enabling one of the other devices in the Device Manager, such as a network card, or simply disconnecting and reconencting a USB mouse), it works for another extension time.

After a prolonged "no-load" period (i.e. time when it is not displayed in the Device Manager), it re-apperas in the Device Manager, but now with the yellow exclamation mark, no sounds can be heard on the machine, and the only way to get the sound back is re-booting and entering into the above-described game.

Perhaps someone has an idea what I can try to do to repair this strange and annoying behaviour?

Among other trials, I have even re-installed Windows XP once, in an attempt to correct it, but of no avail.

Tony