Check if you have removed Java from your system as it is a must required for CRWS. Also if you have changed the password on the router or closed CRWS using X on the browser you may have to again set the password in CRWS. In Microsoft Windows XP, CRWS may not work properly if invoked with Internet Explorer browser which does not have built-in Microsoft Virtual Machine (MVM). Microsoft Windows XP does not come with MVM by default and the Service Packs may or may not contain MVM (SP1 comes with MVM and SP1a does not). To overcome this, invoke CRWS in Netscape browser version 4.5 or 4.7x, which
has built-in support for Java and JavaScript.
CRWS temporarily sets the vty line for login local, but upon exiting from CRWS, the router is returned to the state it was in. Hence, if some other login type (other than login local) is configured on the router before invoking CRWS, then you will be unable to Telnet into the router while CRWS is running. You can avoid this problem by configuring a username and password for the Telnet session, since this will be necessary when "login local" is in effect. You can also configure this username and password by using the Router Password opton in CRWS.
Following links amy help you
http://www.cisco.com/en/US/products/sw/netmgtsw/ps2076/prod_troubleshooting_guide09186a0080132c3c.html
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_fix/800/tgcrws32.htm
http://www.cisco.com/en/US/products/sw/netmgtsw/ps2076/