First guess, it's an out of memory problem. You'll probably need to allocate more memory. PermGen might be the thing. Try googling 'minecraft permgen' for some options.
Allocating more memory through the launcher might do it too.
However, realize that Tekkit's current recommended releases are UNSTABLE and do have a memory leak related to Project Red. For some reason they didn't include the fixes in version e, even after being told about the issue beforehand. Don't know why they're dragging their feet on this issue.