Created attachment 12665 [details]
IDE Log as instructed by Error message

Some other information that may be of use. 

Firstly, the version number! Version 3.5.1 build 200307302351 
downloaded along with the Sun Java SDK v1.4.2. I set-up the SDK and 
the NetBeans interface using the default installation locations and 
then downloaded and installed all the latest available modules from 
the web site, including the hot fixes. I installed these in the 
global catalogue. 

I am running Windows XP Professional SP1 with all the latest 
security patches and updates (too many to list here).

I am also running Norton Internet Security 2002 with the personal 
firewall and anti-virus enabled. This has been giving me trouble in 
other areas, specifically with the database engines I have 
installed. I have turned the security down as far as I dare to just 
block known trojans, alerts on unused ports and straightforward 
monitoring. Unfortunately, I can't uses a proxy server as Win XP 
doesn't have one and my ISP doesn't provide a proxy service and I 
can't seem to allow individual ports to communicate and block the 
rest until I need them. The problems with the DB engines seem to 
have been cured and NetBeans connects OK, but it may perhaps be 
significant.

Database engines I have installed are Oracle 9i Personal Edition 
(9.2.1.0), IBM DB2 Personal Edition (8 SP3), SQL Server 2000 
Developement Edition (SP3) and MySQL MaxDB version 7.5.0.5. I also 
have MS Access 2002 with all the latest updates. The first 2 are 
heavily dependent on Java and have installed different machines. The 
Java machine installed with Oracle is 1.3.1 and this appears in the 
path and in the Class path whereas NetBeans does not. This might be 
significant.

Finally, I have MinGW with its version of gcj and java machine 
installed.

The error would appear to be spasmodic and not easily repeatable.

Reassigning to usersguide - hopefully this is the right category.

switching to core/help system. 

It seems to me that others have run across these kinds of intermittent
things before and not been able to reproduce them, but I can't find
the issue number.

that's the well known problem (bug) in Swing HTML renderer.  Jesse
probably knows the JDK bug number

Actually Tim is probably the one who knows what to mark this duplicate of.

I haven't seen this particular exception before. It's just some
random, unreproducible exception in Swing HTML rendering code, I
suppose. Probably no good way to track it down.

Well, not sure how reproducible it is, but this is a simple missing null-check in 
javax.swing.text.html.HRuleView:

HRuleView calls:
            Color bg = getContainer().getBackground();

And View.getContainer() is implemented as:
    public Container getContainer() {
	View v = getParent();
	return (v != null) ? v.getContainer() : null;
    }

I'll file a JDK bug on it.

Reassigning to Marek, new owner of output window and help system

JDK bug. Closing. (You can search JDK bug database to find status.)

Hold on, need the actual bug # to be listed here. *You* should search
the bug database. Or Tim did you already file some bug for this?

Tim did you file bug to JDK? I did not find any but only read only
copy of this issue ie.
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4972467 but this is
not issue Tim promised to file.

Tim did you file bug against JDK or not?

I filed issue #5082016 in JDK bug database.

reopening, just so that it's easier to track the issue. I set the
target milestone to "future", so hopefully that does not reflect on
Marek's bug counts. :)

Sorry Patrick, but if it's not a bug we can fix, we do not want it
open. Could keep a separate list somewhere of JDK bugs that might
affect help.

*** Issue 48849 has been marked as a duplicate of this issue. ***

verified in NB4.1(200501241900)