The Longest Stack Trace

Unattended IE 8 with some opened page was spiking 50% CPU on a 2 processor PC. We saved the dump file and it had the longest HTML processing user space thread stack we had ever seen:

0:000> !runaway
 User Mode Time
  Thread       Time
  17:f18       0 days 14:13:41.290
  23:6b0       0 days 0:00:41.309
   4:c88       0 days 0:00:29.031
  10:129c      0 days 0:00:03.853
   3:126c      0 days 0:00:02.620
  16:f98       0 days 0:00:01.934
  18:f8c       0 days 0:00:00.702
   2:cd4       0 days 0:00:00.280
   8:c40       0 days 0:00:00.109
   7:1348      0 days 0:00:00.093
  11:ee4       0 days 0:00:00.015
  24:490       0 days 0:00:00.000
  22:d98       0 days 0:00:00.000
  21:104c      0 days 0:00:00.000
  20:1090      0 days 0:00:00.000
  19:f60       0 days 0:00:00.000
  15:1150      0 days 0:00:00.000
  14:1048      0 days 0:00:00.000
  13:d28       0 days 0:00:00.000
  12:c68       0 days 0:00:00.000
   9:ab0       0 days 0:00:00.000
   6:69c       0 days 0:00:00.000
   5:c28       0 days 0:00:00.000
   1:1264      0 days 0:00:00.000
   0:fa8       0 days 0:00:00.000

0:017:x86> kL 100
ChildEBP RetAddr
0c3b6f48 70072d55 mshtml!CPtsClient::CreateParaclient+0x9
0c3b6f9c 70072288 mshtml!Ptls5::FsConductCensusZooCore+0x30a
0c3b7094 70071720 mshtml!Ptls5::FsConductCensusZooCore+0x62f
0c3b70d4 70072647 mshtml!Ptls5::FsConductCensusZooCore+0x9e1
0c3b71a4 700ce813 mshtml!Ptls5::FsFormatZooCore+0x2f6
0c3b71d8 700cc65b mshtml!Ptls5::FsFormatZoo+0x51
0c3b730c 700cc147 mshtml!Ptls5::FsCreateSubpageCore+0x6f7
0c3b733c 700ccb58 mshtml!Ptls5::FsCreateSubpage+0x82
0c3b73fc 700c9640 mshtml!Ptls5::FsGetSavedPel+0x6ce
0c3b751c 700cae11 mshtml!Ptls5::FsFormatPelCore+0x73d
0c3b75f0 700cb347 mshtml!Ptls5::FsAdjustPageVertical+0x58e
0c3b7690 700c9e1d mshtml!Ptls5::FsAdjustPageVertical+0x15cb
0c3b76e4 700cd0e1 mshtml!Ptls5::FsDuplicateParaFormatResult+0x2be
0c3b778c 700cf796 mshtml!Ptls5::FsFormatOrReusePara+0x400