Winzip doesn't have a firewall; it is a program to compress/decompress files.
I 've gone through your bug report once more; the listening port is 2661 and not 48821 as you said in your post.
Possible programs with firewall are McAfee, Norton, AOL, to name a view.
Here is an example of my bug report:
Detail: Example
-- listing session information --
Current thread: AWT-EventQueue-0
Active Threads: 22
Uptime: 16:51
Is Connected: true
Number of Ultrapeer -> Ultrapeer Connections: 0
Number of Ultrapeer -> Leaf Connections: 0
Number of Leaf -> Ultrapeer Connections: 5
Number of Old Connections: 0
Acting as Ultrapeer: false
Acting as Shielded Leaf: true
Number of Active Uploads: 0
Number of Queued Uploads: 0
Number of Active Managed Downloads: 1
Number of Active HTTP Downloaders: 1
Number of Waiting Downloads: 48
Received incoming this session: true
Number of Shared Files: 32
Guess Capable: true
Received Solicited UDP: true
SIMPP version: 52
Port Stable: true
FWT Capable: true
Last Reported Port: 14192
External Port: 14192
IP Pongs Received: 47
Number of Content Response URNs: 0
Number of CreationTimeCache URNs: 33
VF Byte Cache Size: 0
VF Verify Cache Size: 0
VF Queue Size: 0
ByteBuffer Cache Size: 8646
Number of Waiting Sockets: 0
Number of Pending Timeouts: 2
Do you have any of those programs mentioned above on your computer?
The firewall problem must originate from somewhere...
