stm32程序无法下载

使用SWD模式，先开始没有问题，用了一段时间，突然程序下载不进去了
显示Could not stop Cortex-M device! Please check the JTAG cable
详细信息如下：
Load "C:\Documents and Settings\lenovo\桌面\RC530\RC530(硬件NSS)\Project\Output\test.AXF"
* JLink Info: Device "STM32F107RC" selected (256 KB flash, 20 KB RAM).
Set JLink Project File to "C:Documents and Settingslenovo桌面RC530RC530(硬件NSS)ProjectJLinkSettings.ini"

JLink info:
------------
DLL: V4.35b, compiled Sep  2 2011 18:34:46
Firmware: J-Link ARM V8 compiled Sep  2 2011 17:54:36
Hardware: V8.00
S/N : 20100213
Feature(s) : RDI,FlashDL,FlashBP,JFlash,GDBFULL

* JLink Info: Found SWD-DP with ID 0x1BA01477
* JLink Info: TPIU fitted.
* JLink Info: ETM fitted.
* JLink Info:   FPUnit: 6 code (BP) slots and 2 literal slots
* JLink Info: Found Cortex-M3 r1p1, Little endian.
ROMTableAddr = 0xE00FF003
* JLink Info: Found SWD-DP with ID 0x1BA01477
* JLink Info: TPIU fitted.
* JLink Info: ETM fitted.
* JLink Info:   FPUnit: 6 code (BP) slots and 2 literal slots
* JLink Info: Found Cortex-M3 r1p1, Little endian.
**JLink Warning: CPU could not be halted
我对电路做了检查发现复位脚一直为低电频，即stm32一直处于内部复位状态，检查了外部的阻容电路没有问题，但是外部的上拉无法将复位脚拉高，怎么回事呢？？有人遇到过这种情况么？？？