field value display incorrect,see the following image.

[Linked Image]

run pl/sql 9.0 or above at win7 ,you can find the problem

Can you go to Help > Support Info, press the 'Copy all pages' button on this info screen, and paste this text into an e-mail reply?

--- Info ---

PL/SQL Developer
Version 9.0.6.1665
01.110170 - Unlimited user license
Windows 7 (64-bit) 6.1 Build 7601 (Service Pack 1)

Physical memory : 4,193,528 kB (2,791,356 available)
Paging file : 4,194,304 kB (4,194,304 available)
Virtual memory : 2,097,024 kB (1,934,620 available)

Parameters
C:\Program Files\PLSQL\plsqldev.exe

Preferences
Session mode: Multi
OCI Library:
Use OCI7: False
Allow Multiple Connections: False

Preference Files
C:\Program Files\PLSQL\Preferences\Default\Default.ini
C:\Users\0800718\AppData\Roaming\PLSQL Developer\Preferences\0800718\default.ini

Plug-Ins
*CnPlugin v1.5 (C:\Program Files\PLSQL\PlugIns\CnPlugin.dll)
*PL SQL MFC Demo (C:\Program Files\PLSQL\PlugIns\Paste.dll)
(* is Active)

Aliases
20101214111334-HHS20101214111328-HUTV_1520101020115024-HRP_11520101020115024-HUTV_1520101020115020-HUTV_1520100805165540-HUTV_1620100805165539-HUTV_16HUTV_DEV
clean
CSM_ORA_TEST
edition_bj
edition_cs
...

Homes
OraHome81 (C:\oracle\ora81)

DLLs
C:\oracle\ora81\bin\oci.dll

TNS File
C:\oracle\ora81\Network\Admin\tnsnames.ora

Using
Home: OraHome81
DLL: C:\oracle\ora81\bin\oci.dll
OCI: Version 8.1
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0

Character Sets
Character size: 2 byte(s)
CharSetID: 852
NCharSetID: 2000
Unicode Support: True
NLS_LANG: SIMPLIFIED CHINESE_CHINA.ZHS16GBK
NLS_CHARACTERSET: ZHS16GBK
NLS_NCHAR_CHARACTERSET: AL16UTF16

--- Registry ---

SOFTWARE\ORACLE
NLS_LANG = NA
ORACLE_GROUP_NAME = Oracle - OraHome81
ORACLE_HOME = C:\oracle\ora81
ORACLE_HOME_NAME = OraHome81

SOFTWARE\ORACLE\ALL_HOMES
DEFAULT_HOME = OraHome81
HOME_COUNTER = 1
LAST_HOME = 0

SOFTWARE\ORACLE\ALL_HOMES\ID0
NAME = OraHome81
NLS_LANG = NA
PATH = C:\oracle\ora81

SOFTWARE\ORACLE\HOME0
ID = 0
NLS_LANG = SIMPLIFIED CHINESE_CHINA.ZHS16GBK
ORACLE_GROUP_NAME = Oracle - OraHome81
ORACLE_HOME = C:\oracle\ora81
ORACLE_HOME_KEY = Software\ORACLE\HOME0
ORACLE_HOME_NAME = OraHome81

--- Path ---

C:\oracle\ora81\bin
C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common
C:\Program Files\Common Files\Microsoft Shared\Windows Live
C:\Program Files (x86)\Common Files\Microsoft Shared\Windows Live
C:\Windows\system32
C:\Windows
C:\Windows\System32\Wbem
C:\Windows\System32\WindowsPowerShell\v1.0\
C:\Program Files (x86)\Sybase\PowerDynamo\win32
C:\Program Files (x86)\Sybase\Shared\PowerBuilder
C:\Program Files\Sybase\SQL Anywhere 8\win32
C:\Program Files\Sybase\Shared\win32
C:\Program Files\Sybase\Shared\Sybase Central 4.1
C:\Program Files\Sybase\Shared\PowerBuilder
C:\Program Files (x86)\Windows Live\Shared
C:\strawberry\c\bin
C:\strawberry\perl\bin
C:\Program Files (x86)\QuickTime\QTSystem\
C:\Program Files (x86)\Java\jdk1.5.0_11\bin
C:\Program Files\TortoiseSVN\bin
C:\Program Files (x86)\Microsoft Visual Studio\Common\Tools\WinNT
C:\Program Files (x86)\Microsoft Visual Studio\Common\MSDev98\Bin
C:\Program Files (x86)\Microsoft Visual Studio\Common\Tools
C:\Program Files (x86)\Microsoft Visual Studio\VC98\bin

====
this part is the content of tnsnames.ora.
====

You should probably upgrade to an Oracle10g client. My guess is that this is an Oracle 8.1 client issue.

problem still exists after upgrade,
so i think this is not the correct way to solve this problem.

by the way: the field can display correct on plsql 8.0

Can you again go to Help > Support Info, press the 'Copy all pages' button on this info screen, and paste this text into an e-mail reply?