Mail about select

Dear Friends,
   I have two tables

1. "Radius"
      Table    = radius
+----------------------------------+----------------------------------+-------+

|              Field               |              Type                |
Length|
+----------------------------------+----------------------------------+-------+

| uname                            | char()
|   256 |
| logdate                          | date
|     4 |
| logtime                          | time
|     8 |
| duration                         | int4
|     4 |
| status                           | char()
|    20 |
| nasadd                           | char()
|    20 |
| port                             | int4
|     4 |
| bytesin                          | int4
|     4 |
| bytesout                         | int4
|     4 |
| packin                           | int4
|     4 |
| packout                          | int4
|     4 |
| misc                             | int4
|     4 |
+----------------------------------+---------------------------------

2) "radiustemp" with the same structure
now i am firing a query like this:

select r.uname from radius r, radiustemp rt where r.uname<>rt.uname and
r.logdate<>rt.logdate and r.logtime<>rt.logtime;

After some time i get  response
"Segmentation Error"
core(sumped)

can any one help what is the error in this query.

Thanks in advance for your kind help.
Regards,
Vikrant