I've had a problem with one brand/model of thumbdrive/flashdrive/whatever you want to call it when plugged into USB ports on laptops (laptops running on A/C power).

The thumbdrive in question is a Sandisk MiniCruzer 512mb (two different units tested). It fails (isn't seen by WinXP) when plugged into the built in USB 1.1 ports of an HP Presario 906US, or into a generic USB 2.0 PCCARD adapter on a Toshiba. The thumbdrive works fine when plugged into a desktop computer's USB port (either 1.1 or 2.0) and when plugged into a powered USB 2.0 hub off the Toshiba/PCCARD port.

In either of the problem scenarios, a Lexar 128mb thumbdrive works fine, and a Lexar 512mb thumbdrive works some of the time (depends on whether or not something else is plugged into the second USB port).

Which leads me to wonder if I'm seeing a power problem. Do 512mb thumbdrives require that much more juice, or are the USB ports on a laptop marginal power providers?

I resolved a problem with an external CDR/W drive on the Toshiba setup by attaching it through the powered hub, which adds weight to my belief that available power is a problem.

So...anyone else seen/resolved this type of problem?