急，ASP图片上传问题 - 编程论坛

本地测试中doc|xls|ppt和JPG上传都是正常都，但放到服务器上后只有doc|xls|ppt上传正常，JPG大小在50K左右以上时就超时了，而其他文件几M也正常，这是为什么啊？
贴上代码：
<%@LANGUAGE="VBSCRIPT" CODEPAGE="936"%>

<html>
<head>
<title>文件上传</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>
<body>
<p>
<%
dim upload,f_folder,file,formPath,iCount,filename,fileExt,filesizemin,filesizemax

filesizemin=100
filesizemax=500000*1024
set upload=new upload_5xSoft '建立上传对象
f_folder=upload.form("upfilefolder")
d_time=upload.form("d_time")
d_zz=upload.form("d_zz")
d_bt=upload.form("d_bt")
d_sm=upload.form("d_sm")

'********************************列出所有上传文件***************************************************
For each formName in upload.objFile
set file=upload.file(formName)
If file.filesize>0 then

    '********************************检测文件大小***************************************************
    If file.filesize<filesizemin Then
        response.write "你上传的文件太小了　[ <a href=# onclick=history.go(-1)>重新上传</a> ]"
    ElseIf file.filesize>filesizemax then
        response.write "文件大小超过了 "&filesizemax&"字节限制　[ <a href=# onclick=history.go(-1)>重新上传</a> ]"
    End If

    '********************************检测文件类型****************************************************
    fileExt=ucase(right(file.filename,4))
    uploadsuc=false
    Forum_upload="RAR|ZIP|SWF|JPG|PNG|GIF|DOC|TXT|CHM|PDF|ACE|MP3|WMA|WMV|MIDI|AVI|RM|RA|RMVB|MOV|XLS"
    Forumupload=split(Forum_upload,"|")
    for i=0 to ubound(Forumupload)
        if fileEXT="."&trim(Forumupload(i)) then
            uploadsuc=true
            exit for
        else
            uploadsuc=false
        end if
    next
    if uploadsuc=false then
        response.write "文件格式不正确　[ <a href=# onclick=history.go(-1)>重新上传</a> ]"
        response.end
    end if

    '********************************建立文件上传的目录文件夹****************************************
    Set upf=Server.CreateObject("Scripting.FileSystemObject")
    If Err<>0 Then
        Err.Clear
        response.write("您的服务器不支持FSO")
        response.end
    End If

    If upf.FolderExists(Server.MapPath("../"&f_folder))=False Then
            upf.CreateFolder Server.MapPath("../"&f_folder)
    End If
    f_ftn="../"&f_folder
    Set upf=Nothing

    '********************************保存上传文件至文件夹*****************************************
    randomize
    ranNum=int(900*rnd)+100
    filename=f_ftn&"/"&day(now)&"_"&ranNum&"_"&file.filename
    if file.filesize>filesizemin and file.filesize<filesizemax then
    file.SaveAs Server.mappath(filename)
    dim conn1
    set conn1=CreateObject("ADODB.Connection")
    conn1.Open "PROVIDER=SQLOLEDB;DATA SOURCE=(local);UID=sa;PWD=111;DATABASE=website"
    sql = "insert into xiazai_biao(d_bt,d_lj,d_sm,d_time,d_zz) values('"&d_bt&"','"&filename&"','"&d_sm&"','"&d_time&"','"&d_zz&"')"
    conn1.execute(sql)
    conn1.close
    set conn = nothing
    iCount=iCount+1
    end if
set file=nothing
end if
next
set upload=nothing '删除此对象

response.write ("文件上传成功! <a href=# onclick=history.go(-1)>继续上传</a>")
%>
</p>

</body>
</html>
<script type="text/javascript" ></script>