GWT + Eclipse doesn't work. Attempted to beginRule: R/, does not match outer scope rule

Hi,
I have a trouble with Eclipse and GWT.
My GWT projects don't work. All of them. They compile, but don't run
in hosted mode.
When I start Eclipse I receive popup with error. In eclipse error log
I have this:
java.lang.IllegalArgumentException: Attempted to beginRule: R/, does
not match outer scope rule: P/MySmartGWT
at org.eclipse.core.runtime.Assert.isLegal(Assert.java:63)
.....
And it is for all gwt projects.

When I run project I receive a link, for example
http://localhost:8888/MySmartGWT2.html?gwt.codesvr=127.0.1.1:9997, but
when I open it in FireFox - nothing happens. There are not logs,
errors or something like that.

I use Ubuntu 9.10, Eclipse 3.5, GWT 2.0. In some project I am playing
with SmartGWT. Source control - mercurial.

Best regars,
Oleg.

P.S. I know that my English is not very well, but I am learning it now.