System Description: Windows 2000 service pack 4, RAM 256MB

First I installed the personal edition of oracel 9i release 2
(9.2.0.1.0) on the system. the installation went off smoothly. I can
connect to the database using SQL plus. I can create tables etc. I can
connect to thej database using the followinf username/pwd :
dbuser/oracle
system/oracle (NOT system/manager)
scott/tiger

Then I installed Oracle developer suite 9i release 2 on the system.
the installation was completed successfully. Then I opened the forms
developer program and tried to RUN a forms builder application.The
first time it asked me to log in to the database. I logged in using
the "dbuser/oracle" username/pwd combination. Then it went thru the
Java Initiator procedure. After this the web browser was started and
the applet was initialized. and then suddenly  there is a popup box
ie. a connect dialog box with an error message at the top. The error
message is as follows
ORA:12560 TNS protocol adapter error
the dialog box has <DBUSER> in the "Connect as" field. when i re-enter
the password , it again displays the same error message.
if i enter the oracle database service SID i.e. "orcl" in my case it
displays again the same Connect dialog box  with the following error
message
ORA:12514 unable to resolve service name

i followed the instructions given at the bottom of the following link
for installing both the database and the developer suite

http://www.course.com/cdkit/installinstructionsguideto9i.cfm

after searching thru web i set the TNS_ADMIN environmental variable as
follows
TNS_ADMIN=C:\oracle\Oradev\network\admin;C:\oracle\po92\network\admin

but even this did not work. Also i changed the loopback IP address in
the file
C:\oracle\Oradev\network\admin\tnsnames.ora from 127.0.0.1 to the name
of my machine i.e. oracle2.
even this did not work.

Please let me know if u have u any specific steps tht i can follow to
fix this problem.
thank you

Easiest thing to do. is edit the tnsnames.ora file in
C:\oracle\Oradev\network\admin. Add this alias
myDB =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME=orcl)
    )
  )

assuming that "orcl" is your SID. Please confirm the port also.
default is 1521 but you can change it also. ( i assumed you havn't
changed it) Try this if it doen't work put the same thing in
tnsnames.ora file in C:\oracle\po92\network\admin. Now you this alias
"myDB" while it asks the username, password and service_name. I have
faced this problem. Reason for happening is because of ORACLE_HOME in
you registry file. You can edit that too to make sure where it should
point to. Ideally TNS_ADMIN should solve it, but at times on windows
machine it creates problem. If this thing doesn't please let me know
the values in sqlnet.ora file at same location (
C:\oracle\po92\network\admin and C:\oracle\Oradev\network\admin ).

Thanks
Alok

I don;t how to answer a question. That's why i added it as comment. hope it helps.