Yep I had once that problem (the highlight thing, not sure about the volume icon since I don't use it) and corrected it by not installing one item on the Windows Update (using Winds 2000):
810649: Actualización de seguridad
Tamaño de la descarga: 3,5 MB, 2 minutos
Esta actualización contiene diversas correcciones de los componentes de Windows, cuyo objetivo es ofrecer una mejor compatibilidad predeterminada con otros exploradores Web distintos de Internet Explorer. Consulte el artículo 810649 de Microsoft Knowledge Base (KB). Descárguela ahora para mejorar la interacción de ciertos componentes de Windows con exploradores predeterminados distintos de Internet Explorer. Una vez instalado este elemento, puede que deba reiniciar el equipo. Esta actualización no puede desinstalarse. Más información... Es posible que este sitio esté en inglés.
Translated with babelfish:
810649: Security update
Size of the download: 3.5 MB, 2 minutes
This update contains diverse corrections of the components of Windows, whose objective is to offer one better compatibility predetermined with other explorers Web different from Internet Explorer. Consult article 810649 of Microsoft Knowledge Base (KB). Descárguela now to improve the interaction of certain components of Windows with predetermined explorers different from Internet Explorer. Once installed east element, it can that must reinitiate the equipment. This update cannot be desinstalar. More information...
Hope this helps, 'cos it pissed me off when I didn't knew what was going wrong... The funny is that this item is suppossed to increase compatibility, but what it really does it's messes every thing.
Best regards,
Mguel
PS: Edited: "installing one item on win2000 SP3" for "installing one item on the Windows Update" since the problem didn't happen if I installed only SP3... it appeared when doing the windows update.