This problem is due to the presence of Cisco bug ID CSCse00756.
When this issue occurs, downloads from the Internet do not complete successfully.
This issue is mostly seen on these PIX/ASA firewall versions:
The downloads work on some mirror sites but appear to fail consistently from a Microsoft Windows 2000 server with Microsoft Internet Explorer 6.0 whenever URL filtering is enabled.
Note: Downloads with Netscape, Opera or Mozilla Firefox work occasionally.
Disable URL filtering in order to resolve this issue in these PIX/ASA firewall versions temporarily:
This issue is fixed in these PIX/ASA firewall versions:
In order to download the suggested PIX/ASA firewall versions, visit the Cisco Downloads.