some errors while "make check"

Hi.
when I ran "make check" in the build directory of rtt, i got one(core-test) failed as the message showed below.
Is it critical to application of rtt? And how can i fix it?

root@itmlcc:/home/lcc/share/orocos-rtt-1.8.0/img# make check
[ 9%] Built target dev-test
[ 9%] Built target prep-cpf
[ 27%] Built target core-test
[ 45%] Built target task-test
[ 54%] Built target event-test
[ 72%] Built target taskcontext-test
[ 81%] Built target parser-test
[100%] Built target program-test
[100%] Built target state-test
UpdateCTestConfiguration from :/home/lcc/share/orocos-rtt-1.8.0/img/tests/DartConfiguration.tcl
Start processing tests
UpdateCTestConfiguration from :/home/lcc/share/orocos-rtt-1.8.0/img/tests/DartConfiguration.tcl
Test project /home/lcc/share/orocos-rtt-1.8.0/img/tests
Constructing a list of tests
Done constructing a list of tests
Changing directory into /home/lcc/share/orocos-rtt-1.8.0/img/tests
1/ 8 Testing core-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/core-test
Test timeout computed to be: 9.99988e+06
....F.F...................

time_test.cpp:170:Assertion
Test name: TimeTest::testTimers
assertion failed
- Expression: timer.isArmed( 0 )

time_test.cpp:242:Assertion
Test name: TimeTest::testTimerPeriod
assertion failed
- Expression: timer.occured[2].first == 3

Failures !!!
Run: 24 Failure total: 2 Failures: 2 Errors: 0
-- Process completed
***Failed
2/ 8 Testing task-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/task-test
Test timeout computed to be: 9.99988e+06
...............

OK (15)
-- Process completed
Passed
3/ 8 Testing event-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/event-test
Test timeout computed to be: 9.99988e+06
.....................

OK (21)
-- Process completed
Passed
4/ 8 Testing taskcontext-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/taskcontext-test
Test timeout computed to be: 9.99988e+06
............................

OK (28)
-- Process completed
Passed
5/ 8 Testing parser-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/parser-test
Test timeout computed to be: 9.99988e+06
..............

OK (14)
-- Process completed
Passed
6/ 8 Testing program-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/program-test
Test timeout computed to be: 9.99988e+06
...................

OK (19)
-- Process completed
Passed
7/ 8 Testing state-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/state-test
Test timeout computed to be: 9.99988e+06
........

OK (8)
-- Process completed
Passed
8/ 8 Testing dev-test
Test command: /home/lcc/share/orocos-rtt-1.8.0/img/tests/dev-test
Test timeout computed to be: 9.99988e+06
..

OK (2)
-- Process completed
Passed

88% tests passed, 1 tests failed out of 8

The following tests FAILED:
1 - core-test (Failed)
Errors while running CTest
make[3]: *** [tests/CMakeFiles/check] Error 8
make[2]: *** [tests/CMakeFiles/check.dir/all] Error 2
make[1]: *** [tests/CMakeFiles/check.dir/rule] Error 2
make: *** [check] Error 2

And, there is another strange "makecheck" problem. When I ran "make check" in build directory of kdl 1.0.0(I got it from svn), sometimes 100% test passed, but sometimes it showed the failed message below. How it happened and How can I fix it?

root@itmlcc:/home/lcc/share/kdl/build# make check
UpdateCTestConfiguration from :/home/lcc/share/kdl/build/tests/DartConfiguration.tcl
Start processing tests
UpdateCTestConfiguration from :/home/lcc/share/kdl/build/tests/DartConfiguration.tcl
Test project /home/lcc/share/kdl/build/tests
Constructing a list of tests
Done constructing a list of tests
Changing directory into /home/lcc/share/kdl/build/tests
1/ 3 Testing framestest
Test command: /home/lcc/share/kdl/build/tests/framestest
Test timeout computed to be: 9.99988e+06
......

OK (6)
-- Process completed
Passed
2/ 3 Testing kinfamtest
Test command: /home/lcc/share/kdl/build/tests/kinfamtest
Test timeout computed to be: 9.99988e+06
....root(q_nr: 0)

root(q_nr: 0)
Segment1(q_nr: 0)
Segment3(q_nr: 1)
Segment4(q_nr: 2)

Segment2(q_nr: 0)

root(q_nr: 0)
Segment1(q_nr: 0)
Segment3(q_nr: 1)

Segment2(q_nr: 0)

root(q_nr: 0)
Segment1(q_nr: 0)
Segment3(q_nr: 1)

Segment2(q_nr: 0)
Chain1Segment0(q_nr: 2)
Chain1Segment1(q_nr: 3)
Chain1Segment2(q_nr: 4)
Chain1Segment3(q_nr: 5)
Chain1Segment4(q_nr: 6)
Chain1Segment5(q_nr: 7)
root(q_nr: 0)
Segment1(q_nr: 0)
Segment3(q_nr: 1)
Segment4(q_nr: 2)

Segment2(q_nr: 0)
Tree2Segment1(q_nr: 3)
Tree2Segment3(q_nr: 3)

Tree2Segment2(q_nr: 4)
Tree2Chain1Segment0(q_nr: 5)
Tree2Chain1Segment1(q_nr: 6)
Tree2Chain1Segment2(q_nr: 7)
Tree2Chain1Segment3(q_nr: 8)
Tree2Chain1Segment4(q_nr: 9)
Tree2Chain1Segment5(q_nr: 10)
OK (4)
-- Process completed
Passed
3/ 3 Testing solvertest
Test command: /home/lcc/share/kdl/build/tests/solvertest
Test timeout computed to be: 9.99988e+06
....F

solvertest.cpp:315:Assertion
Test name: SolverTest::FkPosAndIkPosTest
assertion failed
- Expression: 0<=ret

Failures !!!
Run: 4 Failure total: 1 Failures: 1 Errors: 0
-- Process completed
***Failed

67% tests passed, 1 tests failed out of 3

The following tests FAILED:
3 - solvertest (Failed)
Errors while running CTest
make[3]: *** [tests/CMakeFiles/check] Error 8
make[2]: *** [tests/CMakeFiles/check.dir/all] Error 2
make[1]: *** [tests/CMakeFiles/check.dir/rule] Error 2
make: *** [check] Error 2

Best Regards.
Jack Lee