Sometimes, when using an "R snippet (Local)" node the font in eclipse becomes corrupted on exit from the node configuration dialogue. This is not deterministic and difficult to replicate. It has only happened to me about 5 times in the last 6 months and I use R quite extensively within Knime.
This is related to the following forum post (whcih has a screen shot with an example):
http://tech.knime.org/forum/knime-users/has-anybody-ever-seen-knime-crash-like-this
I am running eclipse 3.6.2 (64bit) and knime 2.5.2 (on Scientific Linux 6.0). I have seen this issue with multiple versions of both eclipse and knime.