No code, apart from the uploaderdatabaseprovider you supplied. I re-created the database table using your sql definition to make sure it wasn't that.
Locally am running IIS7 and SQL Express 05. For testing I am just trying to upload a .doc file about 2 megabytes in size. Am not using ajax in this example. Silverlight mode seems to work, flash and iframe don't.
ASPX page and web.config: (sorry can't see how to insert code)
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
</head>
<body>
<form id="form1" runat="server">
<div>
<CuteWebUI:Uploader ID="Uploader2" runat="server" FileTypeNotSupportMsg="File type not supported"
InsertText="Flash(doesn't work)" OnFileUploaded="FileUploaded" UploadType="Flash">
<ValidateOption AllowedFileExtensions="doc" MaxSizeKB="1024000" />
</CuteWebUI:Uploader>
<CuteWebUI:Uploader ID="Uploader2" runat="server" FileTypeNotSupportMsg="File type not supported"
InsertText="Silverlight(does work)" OnFileUploaded="FileUploaded" UploadType="Silverlight">
<ValidateOption AllowedFileExtensions="doc" MaxSizeKB="1024000" />
</CuteWebUI:Uploader>
<p>
<asp:Literal ID="ltOutput" runat="server" />
</p>
</div>
</form>
</body>
</html>
-- web.config:
<?xml version="1.0"?>
<configuration>
<appSettings>
<add key="CuteWebUI.AjaxUploader.Provider" value="UploaderDatabaseProvider.UploaderSqlServerProvider,UploaderDatabaseProvider"/>
<add key="UploaderDatabase" value="User ID=AjaxUploader_INETUSER;Password=XXXX;Initial Catalog=XXXX;Data Source=localhost\SQLExpress"/>
</appSettings>
<system.webServer>
<modules>
<add name="CuteWebUI.UploadModule" type="CuteWebUI.UploadModule,CuteWebUI.AjaxUploader"/>
</modules>
</system.webServer>
<connectionStrings/>
<system.web>
<pages>
<controls>
<add namespace="CuteWebUI" assembly="CuteWebUI.AjaxUploader" tagPrefix="CuteWebUI"/>
</controls>
</pages>
<!--
Set compilation debug="true" to insert debugging
symbols into the compiled page. Because this
affects performance, set this value to true only
during development.
-->
<compilation debug="true">
</compilation>
<!--
The <authentication> section enables configuration
of the security authentication mode used by
ASP.NET to identify an incoming user.
-->
<authentication mode="Windows" />
<!--
The <customErrors> section enables configuration
of what to do if/when an unhandled error occurs
during the execution of a request. Specifically,
it enables developers to configure html error pages
to be displayed in place of a error stack trace.
<customErrors mode="RemoteOnly" defaultRedirect="GenericErrorPage.htm">
<error statusCode="403" redirect="NoAccess.htm" />
<error statusCode="404" redirect="FileNotFound.htm" />
</customErrors>
-->
</system.web>
</configuration>