I resolved the problem in a sort of an unofficial way. The easiest was reverting the graphics driver from an Nvidia driver (impossible to upgrade to Windows 7-compatible version) to a Windows-provided Standard VGA driver; it later was replaced by another Windows-provided driver by the Windows 7 "upgrade" installation. Then, a charitable soul gave me a Ver.7 of the Toshiba Bluetooth stack driver, which also got moved during the Windows 7 "upgrade". This updated driver was impossible to get neither from Sony, nor from Toshiba.
One thing is clear: this was my first and last Sony Vaio computer. Worse than dismal technical support, non-standard drivers that are not upgradable by Sony or by the peripheral vendor, and a very long list of etc´s. Not to mention that the motherboard of my laptop had to be replaced... twice...