problems reading messages

[Guy Cohen]

Im using imp-3.RC2 and cyrus imap server.
when logging in no messages appear in the inbox. If i send a new massage
and refresh IMP the message shows, thenif i try to view it, I'm getting
and error viewing the requested message. In the imapd log i get:
Apr  9 15:28:03 mail01 imapd[17197]: open: user rcs opened INBOX
Apr  9 15:28:03 mail01 imapd[17197]: SQUAT failed to open index file
Apr  9 15:28:03 mail01 imapd[17197]: SQUAT failed

what can be the problem?