Created attachment 59837 [details]
stacktrace

Build: NetBeans IDE 6.1 Beta (Build 200803050202)
VM: Java HotSpot(TM) 64-Bit Server VM, 1.6.0_04-b12-45-optimized
OS: Mac OS X, 10.5.2, x86_64

User Comments: 
opening an ejb-maven project

Created attachment 59838 [details]
stacktrace

This issue has already 10 duplicates 

Reassigning to new module owner jskrivanek.

Build: NetBeans IDE 6.0.1 (Build 200801291616)
VM: Java HotSpot(TM) Client VM, 10.0-b19
OS: Linux, 2.6.22-14-generic, i386

User Comments: 
Opening a Maven2 project with server setting e.g:

  <properties>
        <netbeans.hint.deploy.server>J2EE</netbeans.hint.deploy.server>
    </properties>

where no such server exists causes NullPointerException. Comment out the hint and you are back in action. This is in Linux with NB 6.0.

Created attachment 60249 [details]
stacktrace

This issue has already -1 duplicates 

It looks like the module provider is returning a FileObject[] that has embedded null values in it.

That seems kind of wrong, but I can protect against that.

http://hg.netbeans.org/main/rev/3bd6536595a2

Created attachment 63267 [details]
stacktrace

This happens when you use a "resources" entry in your pom with something different than "{$basedir}/src/main/resources":

        <resources>
            <resource>
                <directory>${basedir}/src/main/java</directory>
                <includes>
                    <include>**/gwtdto/*.java</include>
                </includes>
            </resource>
            <resource>
                <directory>${basedir}/src/main/resources</directory>
            </resource>
        </resources>

As a workaround comment the resources section with <!--  -->, then open the project and remove the comment. You still
get the NPE upon first click on the project, but it is open.

Reopening - reproduced in NetBeans IDE 6.1 (Build 200805300101)
http://statistics.netbeans.org/exceptions/detail.do?id=126069

It just happened to me in an up to date Netbeans 6.1 installation while trying to open a Maven project with a 

<properties>
   <netbeans.hint.deploy.server>J2EE</netbeans.hint.deploy.server>
</properties>

section.
Once this section is removed, the project opens normally.

this p3 bug was fixed after the 6.1 clone was created... but before the release shipped.

looks like a bug in the exception reporter...

I don't know if it's a different bug but the symptoms are the same as are described and I'm using an up to date Netbeans
6.1 installation with all the updates applied.

*** Issue 154456 has been marked as a duplicate of this issue. ***