I just started to use Portable Thunderbird from a USB drive on a
dual processor Windows XP MacBookPro.
When I start PortableThunderbird it uses 50 percent CPU (one processor)
and does not start thunderbird. When I start a second app, it starts
Thunderbird nicely and exits. The first PortableThunderbird (which keeps
running at full cpu) I can then go and kill without affecting thunderbird.
The problem appears both with 1.07 and 1.5.
Any further testing I can do.