GWT compile fails in IDEA: UserAgentAsserter cannot be resolved - gwt

Question

Moving my development environment to a new laptop and faced the following error (it's never no-hassle process).
So, what I have is: Windows 8, Intellij Idea 12, GWT 2.5.1, configured a simple artifact that only produces a "GWT compile output":
Information: Compilation completed with 6 errors and 0 warnings in 25 sec
Information: 6 errors
Information: 0 warnings
Error: GWT Compiler: The import com.google.gwt.user.client.UserAgentAsserter cannot be resolved
Error: GWT Compiler: UserAgentProperty cannot be resolved to a type
Error: GWT Compiler: The method create(Class<?>) from the type GWT refers to the missing type UserAgentProperty
Error: GWT Compiler: UserAgentProperty cannot be resolved to a type
Error: GWT Compiler: UserAgentProperty cannot be resolved to a type
<-> D:\Projects\MyProject\src\main\java\com\myproject\RichClient.gwt.xml
Error: GWT Compiler: Aborting compile due to errors in some input files
Build on old laptop is working fine (same environment on Win7), although I don't see any differences in my gwt.xml file. Maybe something is missing that was added to old config manually rather than through repository checkout, but now I can only guess. I have tried to remove/comment all the lines from client.gwt.xml that relate to user.agent property setting, like
<set-property name="user.agent" value="gecko1_8,safari"/>
but no changes and I still see the same "6 errors" message.
I would appreciate any clue on why this error may appear. Thanks.
UPD.
Reduced the code of my RichClient.gwt.xml file to
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit 2.5.0//EN" "http://google-web-toolkit.googlecode.com/svn/tags/2.5.0/distro-source/core/src/gwt-module.dtd">
<module rename-to='richclient'>
<!-- Inherit the core Web Toolkit stuff. -->
<inherits name='com.google.gwt.user.User' />
</module>
(no entry point set) and still got the same error.

Answer 1

Found this later. Obsolete jar that was not included in the lib path for the original project but managed to sneak into the newly configured.
Validating units:
[ERROR] Errors in 'jar:file:/D:/Projects/myProject/src/main/webapp/WEB-INF/lib/css3pie-0.1.jar!/com/google/gwt/user/client/UserAgentInfo.java'
[ERROR] Line 19: The import com.google.gwt.user.client.UserAgentAsserter cannot be resolved
[ERROR] Line 23: UserAgentProperty cannot be resolved to a type
[ERROR] Line 23: The method create(Class<?>) from the type GWT refers to the missing type UserAgentProperty
[ERROR] Line 23: UserAgentProperty cannot be resolved to a type
[ERROR] Line 26: UserAgentProperty cannot be resolved to a type
[ERROR] Line 26: UserAgentProperty cannot be resolved to a type
[ERROR] Line 40: UserAgentProperty cannot be resolved to a type
Removing the jar did the trick.