I got my Yubikey from MtGox and I find it small and kind of fragile.
What's the best physical protection for a Yubikey?
Protection against damage when carried in my pocket for example?

@orymh: thank you for the detailed answer.
No one else has access to the computer I use, so I should be fine with sessions of 2 hours.
I also won't click on any links provided in these forums.

Since the MtGox dollar withdrawals are suspended, probably the ASIC miners are dumping BTC on other exchanges,
since they want their investment returned ASAP. Currently there is a 7$ gap between MtGox and Bitstamp, usually
the gap is only around 1$. I wish I hadn't moved by BTC from Bitstamp to MtGox before the news...

Thank you, in the mean time I figured it out. Silly me, didn't notice the session duration setting.
There was no such thing on Bitstamp. Let's try a more advanced question:
If I set the session duration to something like 1-2h, how risky is it (hacking wise)?
I have already set security and withdrawals to TFA with OTP.

Hi there, first post on these forums!
I used to trade on Bitstamp and then moved my BTCs to MtGox.
There is an annoying thing going on: after logging in and spending some time watching clarkmoody and bitcoinity,
in different tabs of Firefox, when I switch back to the open tab with MtGox trade page I find myself logged out.
Actually, when I try to modify my order I have to login again, which can take upto 30s, typing username and long password.
I tried to clear all Firefox cookies and history, as suggested by Mozilla support, but it didn't help.
This loss of login didn't happen on Bitstamp, using the same version of Firefox. Any advice would be welcome.