FYI, I was getting this crash when my {t: {$gte: someTime}} query was at just the wrong time, i.e. when a certain document was going to be in the result set. I tried --repair, and while the first attempt froze my whole machine during indexing (bad disk? power?), a successful --repair run seems to have fixed the problem.

Tue Nov 16 23:25:24 Backtrace:
0x8212f9 0x7fdc251a2c20 0x5b868b 0x5b942b 0x6eb872 0x5fdeaf 0x704cc0 0x708acd 0x8235ef 0x837460 0x7fdc25c98971 0x7fdc2525591d
build_mongodb/bin/mongod(mongo::abruptQuit(int)+0x399) [0x8212f9]
/lib/libc.so.6(+0x33c20) [0x7fdc251a2c20]
build_mongodb/bin/mongod(mongo::Matcher::matchesDotted(char const*, mongo::BSONElement const&, mongo::BSONObj const&, int, mongo::ElementMatcher const&, bool, mongo::MatchDetails*)+0x1fcb) [0x5b868b]
build_mongodb/bin/mongod(mongo::Matcher::matches(mongo::BSONObj const&, mongo::MatchDetails*)+0xeb) [0x5b942b]
build_mongodb/bin/mongod(mongo::CoveredIndexMatcher::matches(mongo::BSONObj const&, mongo::DiskLoc const&, mongo::MatchDetails*)+0xe2) [0x6eb872]
build_mongodb/bin/mongod(mongo::processGetMore(char const*, int, long long, mongo::CurOp&, int, bool&)+0x29f) [0x5fdeaf]
build_mongodb/bin/mongod(mongo::receivedGetMore(mongo::DbResponse&, mongo::Message&, mongo::CurOp&)+0x240) [0x704cc0]
build_mongodb/bin/mongod(mongo::assembleResponse(mongo::Message&, mongo::DbResponse&, mongo::SockAddr const&)+0x14ed) [0x708acd]
build_mongodb/bin/mongod(mongo::connThread(mongo::MessagingPort*)+0x30f) [0x8235ef]
build_mongodb/bin/mongod(thread_proxy+0x80) [0x837460]
/lib/libpthread.so.0(+0x7971) [0x7fdc25c98971]
/lib/libc.so.6(clone+0x6d) [0x7fdc2525591d]

Tue Nov 16 23:25:24 dbexit: