[ic] form gives page () not found error

[Genna Bae]

Hi,

I've just installed interchage-4.8.3 and everything works fine except when I
tried to login or use anything that uses form, I get following error:

Sorry, the page () was not found

The requested page (unspecified error) was not found. You can return to
browsing our catalog, if you wish.

Also, I some how can get into the administrator's page later after clicking
through several pages ahead and going backward by clicking browser's back
button. Still, I can not do anything that uses form.

Is there some kind of module I am missing? How can I found out to fix this
problem.

Thank you,
genna