BUG #4048: Can't install pltcl

The following bug has been logged online:

Bug reference: 4048
Logged by: IP
Email address: ireneusz(dot)pastusiak(at)poczta(dot)fm
PostgreSQL version: 8.3.0
Operating system: Windows XP PL SP2
Description: Can't install pltcl
Details:

-- Executing query:
CREATE LANGUAGE plpythonu;

Query returned successfully with no result in 31 ms.

-- Executing query:
CREATE LANGUAGE pltcl;

ERROR: could not load library "C:/Program
Files/PostgreSQL/8.3/lib/pltcl.dll": unknown error 126

********** Error **********

ERROR: could not load library "C:/Program
Files/PostgreSQL/8.3/lib/pltcl.dll": unknown error 126
SQL state: 58P01

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More details:
1. DLL file is in correct path.
2. ActiveState ActiveTcl 8.5.1.0 installed before PostgreSQL. If ActiveTcl
is installed after PostgreSQL, same problem occurs.