I was able to reproduce with recent 6.6 version, on windows XP Pro 64 bits.
It doesn't seem related to the platform, but at some point, the debugger via the objects tool, tries to evaluate something on the debuggee (application).
This explains why this occurs only when the tool is big enough, if the "Current" is not displayed, the debugger won't evaluate any expression on the debuggee to display those information on the tool's grid.

I assume, this is the evaluation which crashes the debuggee and thus terminate the debugging session. We need to investigate this.