[Joey]

Unfortunately, my bookmark date went wrong again this morning.
It's been like 4 or 5 days since last time I connected my reader to PC.
It lasted longer than before actually but still was not a satisfactory result.
So just give a second call to Sony Reader customer service.
This time, after several minute discussion with software engineers,
the answer turned out this situation is 100% normal.

According to them, since we don't have a built-in clock inside the reader,
everything regarding time is obtained by synchronization with PC.
It's absolutely normal that date and time are reset after a couple of days or weeks.
And days it takes to lose time accuracy vary from devices to devices.

Also, since this should be a software problem, it's possible to be fixed by
a firmware update.
Right now, I can only live up with this minor problem.

Hopefully, the update will come out soon.