I am running the current version of both Silverstripe (2.2) and the E-Commerce module (0.5.1)? And using the PayPalPayment although I don't think this relates to that.
There appears to be an error in the way the SQL is generated, notice the first SELECT is trying to request the data from Product_Live (which does exist) but it isn't listed in the FROM anywhere (not joined to).
FATAL ERROR: DATABASE ERROR: Couldn't run query: SELECT `SiteTree_Live`.*, `Product_Live`.*, `SiteTree_Live`.ID, if(`SiteTree_Live`.ClassName,`SiteTree_Live`.ClassName,'SiteTree') AS RecordClassName, `SiteTree_Live_versions`.AuthorID, `SiteTree_Live_versions`.Version, `SiteTree_Live_versions`.RecordID AS ID FROM `SiteTree_Live` LEFT JOIN `Product_versions` ON `Product_versions`.RecordID = `SiteTree_Live_versions`.RecordID AND `Product_versions`.Version = `SiteTree_Live_versions`.Version WHERE (`SiteTree_Live`.RecordID = 7 AND `SiteTree_Live`.Version = 1) AND (`SiteTree_Live`.ClassName IN ('Product')) ORDER BY Sort | Unknown table 'Product_Live'
At line 397 in C:\lighttpd\htdocs\sapphire\core\model\Database.php
user_error(DATABASE ERROR: Couldn't run query: SELECT `SiteTree_Live`.*, `Product_Live`.*, `SiteTree_Live`.ID, if(`SiteTree_Live`.ClassName,`SiteTree_Live`.ClassName,'SiteTree') AS RecordClassName, `SiteTree_Live_versions`.AuthorID, `SiteTree_Live_versions`.Version, `SiteTree_Live_versions`.RecordID AS ID FROM `SiteTree_Live` LEFT JOIN `Product_versions` ON `Product_versions`.RecordID = `SiteTree_Live_versions`.RecordID AND `Product_versions`.Version = `SiteTree_Live_versions`.Version WHERE (`SiteTree_Live`.RecordID = 7 AND `SiteTree_Live`.Version = 1) AND (`SiteTree_Live`.ClassName IN ('Product')) ORDER BY Sort | Unknown table 'Product_Live',256)
line 397 of Database.php
Database->databaseError(Couldn't run query: SELECT `SiteTree_Live`.*, `Product_Live`.*, `SiteTree_Live`.ID, if(`SiteTree_Live`.ClassName,`SiteTree_Live`.ClassName,'SiteTree') AS RecordClassName, `SiteTree_Live_versions`.AuthorID, `SiteTree_Live_versions`.Version, `SiteTree_Live_versions`.RecordID AS ID FROM `SiteTree_Live` LEFT JOIN `Product_versions` ON `Product_versions`.RecordID = `SiteTree_Live_versions`.RecordID AND `Product_versions`.Version = `SiteTree_Live_versions`.Version WHERE (`SiteTree_Live`.RecordID = 7 AND `SiteTree_Live`.Version = 1) AND (`SiteTree_Live`.ClassName IN ('Product')) ORDER BY Sort | Unknown table 'Product_Live',256)
line 106 of MySQLDatabase.php
MySQLDatabase->query(SELECT `SiteTree_Live`.*, `Product_Live`.*, `SiteTree_Live`.ID, if(`SiteTree_Live`.ClassName,`SiteTree_Live`.ClassName,'SiteTree') AS RecordClassName, `SiteTree_Live_versions`.AuthorID, `SiteTree_Live_versions`.Version, `SiteTree_Live_versions`.RecordID AS ID FROM `SiteTree_Live` LEFT JOIN `Product_versions` ON `Product_versions`.RecordID = `SiteTree_Live_versions`.RecordID AND `Product_versions`.Version = `SiteTree_Live_versions`.Version WHERE (`SiteTree_Live`.RecordID = 7 AND `SiteTree_Live`.Version = 1) AND (`SiteTree_Live`.ClassName IN ('Product')) ORDER BY Sort,256)
line 79 of DB.php
....
SQLQuery->execute()
line 642 of Versioned.php
Versioned::get_version(Product,7,1)
line 1005 of Order.php
Order_Item->__construct(Array)
line 1472 of DataObject.php
DataObject->buildDataObjectSet(MySQLQuery,DataObjectSet,SQLQuery,Order_Item)
line 1452 of DataObject.php
DataObject->instance_get(OrderID = 11,,,,DataObjectSet,)
line 1432 of DataObject.php
DataObject::get(Order_Item,OrderID = 11)
line 356 of Order.php
Order->itemsFromDatabase()
line 373 of Order.php
Order->Items()
call_user_func_array(Array,Array)
line 524 of ViewableData.php
ViewableData->cachedCall(Items,,)
line 565 of ViewableData.php
ViewableData->hasValue(Items)
line 54 of .cacheC..lighttpd.htdocs.ecommerce.templates.Layout.CheckoutPage.ss
include(C:\Documents and Settings\ddeveloper\Local Settings\Temp\silverstripe-cacheC--lighttpd-htdocs\.cacheC..lighttpd.htdocs.ecommerce.templates.Layout.CheckoutPage.ss)
line 190 of SSViewer.php
SSViewer->process(CheckoutPage_Controller)
line 182 of SSViewer.php
SSViewer->process(CheckoutPage_Controller)
line 247 of Controller.php
Controller->defaultAction(11,Array)
line 218 of Controller.php
Controller->run(Array)
line 15 of ModelAsController.php
ModelAsController->run(Array)
line 76 of Director.php
Director::direct(/checkout/11)
line 104 of main.php