gpg: [don't know]: invalid packet (ctb=4c)

[sbhatt]

Hi Group,

    I installed GPG a few weeks back and presently I am decrypting some 
symmetric cipher text. One of the errors that has shown up last night 
(for the first time) is

gpg: [don't know]: invalid packet (ctb=4c)
gpg: [don't know]: invalid packet (ctb=4e)
gpg: [don't know]: invalid packet (ctb=47)

I tried looking in the mail-lists but did not find anything (may be I 
skipped it) but can anybody please let me know why this error occurs and 
wats the workaround for it.

I would really appreciate all help

thanks much
Sid