Explanation:

When Foxhound encounters invalid data ("Value out of range", etc.) when trying to display a sample in the Top Sample of the History page or the Most Recent Sample of the Monitor page, it skips that sample by marking it lost and then looks for an earlier sample to display.

If it performs this process 100 times without finding a valid sample, it gives up an issues an "Internal error: Retry loop failed to find a Top Sample or Most Recent Sample to display." message instead.

Please report this error; see How do I report unexpected errors and exceptions?

If possible, include the diagnostic dumps for the previous exceptions involving invalid data; here is an example:

1. Use the Foxhound Options - 8. Diagnostics - Display Diagnostics button to find the exception id for the "Retry loop failed" exception, 9670 in this case:

9670 - 2012-02-28 13:38:52.695 Full Build 4025a 32470 182a5(182eh2) Internal error: Retry loop failed to find a Top Sample or Most Recent Sample to display.
running for that sampling id. [4-Foxhound_on_old_Dell_XP]

The "Retry loop failed..." exception was preceded by 100 other exception messages; here are the last two...

9668 - 2012-02-28 13:38:52.542 Full Build 4025a 32470 182a3(182eh1) SQLCODE = -158, SQLSTATE = 22003, ERRORMSG() = Value 46116860613593576000 out of range for destination
9669 - 2012-02-28 13:38:52.680 Full Build 4025a 32470 182a3(182eh1) SQLCODE = -158, SQLSTATE = 22003, ERRORMSG() = Value 46116860613593576000 out of range for destination

2. Run adhoc queries to see the associated diagnostic exception dumps (see How do I run adhoc queries on the Foxhound database?):

SELECT * FROM exception_dump WHERE exception_id IN ( 9668, 9669 );

9668,5720,2012-02-28 13:38:52.638,'''182a3'',''(182eh1)'',5,174924,''N'',''Y'','''',48135,141,0,2012-02-25 23:37:06.233,
   ''12.0.1.3457'',''12.0.1.3457'',8192,''Y'',''Y'',''Y'',346348371968,346348371968,346348371968,346348371968,''connected'',
   3,1703587580,2145158597,5064721575,0,4603399663,41,4832,78,17480984,0,0,409567321,62331053,''/xxx/xxx.db'',
   0,746148869,536379770,4294966040,11157,33435808,''synchronous'',''synchronized'',15,4,0,''connected'',46116860613593576,
   5,''Off'',60,2055699670,''xxx'',''2012-01-25 20:23:24.305352'',0,50532,50923,113980,2821290,0,3081824,0,261656,1,0,87,
   0,0,0,0,1230,11,76,0,0,55581,251471,43,15624,6,0\x0d\x0a'

9669,5721,2012-02-28 13:38:52.757,'''182a3'',''(182eh1)'',5,174917,''N'',''Y'','''',61238,145,0,2012-02-25 23:36:15.701,
   ''12.0.1.3457'',''12.0.1.3457'',8192,''Y'',''Y'',''Y'',346348371968,346348371968,346348371968,346348371968,''connected'',
   3,1703536657,2145044617,5061900285,0,4600317839,39,4832,78,17480984,0,0,409305665,62331052,''/xxx/xxx.db'',
   0,746148782,536379770,4294966040,11157,33435808,''synchronous'',''synchronized'',16,4,0,''connected'',46116860613593576,
   5,''Off'',60,2055698440,''xxx'',''2012-01-25 20:23:24.305352'',0,63667,47745,145261,6110614,0,6198114,0,88976,2,0,1455,
   0,0,0,0,1144,12,75,0,0,118312,251428,14,15618,5,0\x0d\x0a'

See also...
How do I report unexpected errors and exceptions?
How do I run adhoc queries on the Foxhound database?
How do I see the schema for adhoc reporting?