From the PyCrypto documentation:
That also means that you cannot reuse an object for encrypting or decrypting other data with the same key.
The issue is that you will have to reinitialize your cipher, or - probably better - to construct separate object instances for encryption and decryption.
from Crypto.Cipher import AES,DES
from Crypto import Random
iv_AES = Random.new().read(AES.block_size)
iv_DES = Random.get_random_bytes(8)
key_AES = 'abcdefghijklmnop'
key_DES = 'abcdefgh'
aese = AES.new(key_AES,AES.MODE_CFB,iv_AES)
aesd = AES.new(key_AES,AES.MODE_CFB,iv_AES)
dese = DES.new(key_DES,DES.MODE_CFB,iv_DES)
desd = DES.new(key_DES,DES.MODE_CFB,iv_DES)
plaintext = 'Hello! World'
print plaintext == aesd.decrypt(aese.encrypt(plaintext))
print plaintext == desd.decrypt(dese.encrypt(plaintext))