I'm running the latest VBOX 1.5.4 on Ubuntu 7.10 (Gutsy) 64-bit version. On a Quad Core Intel Q6600 processor. My guest OS is Win XP SP2 using NAT in the VBox Network Settings.
When I do something VERY network intensive on the guest OS such as running a port scanner or proxy scanner for more than a few minutes, the Virtual Machine core dumps (aborts), and I get the following log:
Log created: 2008-01-04T23:07:56.227929000Z
Executable: /usr/lib/virtualbox/VirtualBox
Arg[0]: /usr/lib/virtualbox/VirtualBox
Arg[1]: -comment
Arg[2]: WindowsXP
Arg[3]: -startvm
Arg[4]: f2981c30-2053-45bd-4b97-76e88f9367f9
!!Assertion Failed!!
Expression: <NULL>
Location : /home/vbox/vbox-1.5/src/VBox/Devices/Network/slirp/tcp_subr.c(1341) VBoxU32PtrHashSlow
NAT pointer hash error. pv=00002aaab036c890 cpvHashUsed=321 cpvHashCollisions=198