If you have encountered some bug please submit your report via the bug tracker. The following additional information is always very appreciated:
Don't forget to check the Capture Kernel and Capture Win32 items of the Capture menu in DbgView program. Check the Log Boot item if you will debug the boot time defragmenter.
Note that DbgView cannot capture information from the user mode driver during the Windows boot process. This is a well known DbgView limitation. The latest version of DbgView cannot also be used on NT 4.0, check this page for an earlier version.