nessus client hangs when restoring detached session

I ran a detached scan on a largish (/22) subnet. When I try to restore
the saved session, the nessus client went through all hosts (I
watched those progress bars complete), after which it hung, right
before switching to the view of the results.

The nessus client was using 99% cpu on the host on which it was
running, and after 24 hours of this I finally killed it.

While it that "hanging" state, I attached a gdb to it and did a
backtrace, and here is what I got:

(gdb) bt
#0  0x0806b931 in be_index_keywords (be=0) at data_mining.c:119
#1  0x0806be78 in read_line (be=0, buf=0x80f0260 "", size=32768)
    at data_mining.c:272
#2  0x0806cce7 in execute_query_flatfile (be=0, query=0x858bca8)
    at data_mining.c:1371
#3  0x0806cf96 in query_backend (be=0, 
    str=0x809aa00 "SELECT %s,severity FROM results") at
data_mining.c:1408
#4  0x0805b285 in subnets_fill (be=0, list=0x8596050) at
report_ng.c:413
#5  0x0805e68a in create_report_window (be=0) at report_ng.c:1294
#6  0x0805ece7 in report_tests_ng (be=0, interrupted=1) at
report_ng.c:1357
#7  0x0806a439 in monitor_input_callback (ctrls=0x8546fa8, fd=6,
condition=0)
    at monitor_dialog.c:595
#8  0x080693fd in idle_socket (ctrls=0x8546fa8) at
monitor_dialog.c:124
#9  0x4035fadf in g_idle_dispatch () from /usr/lib/libglib-1.2.so.0
#10 0x4035e97e in g_main_dispatch () from /usr/lib/libglib-1.2.so.0
#11 0x4035ee59 in g_main_iterate () from /usr/lib/libglib-1.2.so.0
#12 0x4035f0f4 in g_main_run () from /usr/lib/libglib-1.2.so.0
#13 0x4025e6df in gtk_main () from /usr/lib/libgtk-1.2.so.0
#14 0x0808fdc7 in main (argc=1, argv=0xbffff654) at nessus.c:1275
#15 0x4049d4ed in __libc_start_main () from /lib/libc.so.6

Anyone have an idea what might be going on ?

Thanks much,

Gabriel