The remote host is missing an update to ekg announced via advisory DSA 1664-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201664-1

It was discovered that ekg, a console Gadu Gadu client performs insufficient input sanitising in the code to parse contact descriptions, which may result in denial of service. For the stable distribution (etch), this problem has been fixed in version 1:1.7~rc2-1etch2. For the unstable distribution (sid) and the upcoming stable distribution (lenny), this problem has been fixed in version 1:1.8~rc1-2 of libgadu. We recommend that you upgrade your ekg package.