Can *anyone* tell me why a count query would generate a "System.Exception: Too many query rows: 10001" message?

Here's the annotated code:

public List<Transport__c> getDisplay() { Schema.DescribeSObjectResult R = Account.SObjectType.getDescribe(); //Get Describe object for 'ACCOUNT' List<Schema.ChildRelationship> C = R.getChildRelationships(); //Get List of child relationships for 'ACCOUNT' List<Transport__c> transports = new List<Transport__c>(); //initialize list of placeholder objects For (Schema.ChildRelationship child : C) //For each Child relationship -- 52 total { Schema.DescribeSObjectResult R2 = (child.getChildSObject()).getDescribe(); //Get Describe object for the related child object boolean boolQuery = R2.isQueryable(); //Is the Child object Queryable? if (boolQuery) //If so -- 48 total { Transport__c transport = new Transport__c(); //initialize placeholder for this object transport.Text_1_80__c = string.valueOf(child.getChildSObject()); //Get the child's object token and convert it to string transport.Text_2_80__c = string.valueOf(child.getField()); //Get the child's foreign key field token and convert it to string string strObject = string.valueOf(child.getChildSObject()); //ditto string strField = string.valueOf(child.getField()); //ditto string strValue = '0015000000QKSb1AAH'; //hard coded Account ID for testing string strQuery = 'SELECT Count() FROM ' + strObject + ' WHERE ' + strField + ' = \'' + strValue + '\''; //Create SOQL count query string integer intCount = Database.countQuery(strQuery); //execute the SOQL Count Query transport.Title_1_255__c = strQuery; //Display the SOQL query string transport.Text_3_80__c = string.valueOf(intCount); //Display the string value of the count result transports.add(transport); //add this placeholder to placeholder list } } return transports; //send the list to the page for display }