I have tried both as a regular user and as root. Not a superuser account but root exactly.
While googleing, I have found this issue http://www.netbeans.org/issues/show_bug.cgi?id=77609
that seems to be almost identical to what I experience.
./netbeans-5_5-beta-linux.bin -is:log a.log
and examining the log gave the following results:
Log file created by MultiPlatform installer @Mon Jun 19 19:52:20 EEST 2006
Checking the environment variables specifed in the JVM files to find the JVM...
Verifying... /usr/bin/java -cp /tmp/istemp17186170195220/Verify.jar Verify java.vendor java.specification.version
Verification passed for /usr/ using the JVM file /tmp/istemp17186170195220/jdk15unix_sun.jvm.
-cp:p operand is empty
-cp:a operand is empty
checking disk space on the parition /tmp/istemp17186170195220 for /tmp/istemp17186170195220/setup.jar
84389 512 bytes disk blocks required.
132341800 512 bytes disk blocks available on the partition /tmp/istemp17186170195220
Disk space check on the parition /tmp/istemp17186170195220 succeeded.
Extracted Installer JAR archive file size incorrect. archive may be corrupt. Failed to launch the application.
Launch Script can't not be resolved. Run the installer with -is:log <logfile> to view the errors.
so it seems that either there is an error with the embeded archive or it has been corrupted in the download.
As a workaround I have managed to install the Java EE SDK bundled with NetBeans 5.5 and that worked OK. At least for me this is a solution since I was going to use Java EE SDK anyway